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Effect of udder type and calving assistance on weaning traits of beef and dairy×beef calves
Livestock Production Science 81 (2003) 47–56 www.elsevier.com / locate / livprodsci
Effect of udder type and calving assistance on weaning traits of beef and dairy 3 beef calves a, a b c b L.A. Goonewardene *, Z. Wang , M.A. Price , R.-C. Yang , R.T. Berg , b M. Makarechian a
Livestock Development Division, Alberta Agriculture, Food and Rural Development, 204 7000 -113 Street, Edmonton, Alberta, Canada T6 H 5 T6 b Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6 G 2 P5 c Research Division, Alberta Agriculture, Food and Rural Development, 202 7000 -113 Street, Edmonton, Alberta, Canada T6 H 5 T6 Received 15 March 2002; received in revised form 5 September 2002; accepted 16 September 2002
Abstract The effects of udder type, calving assistance (CA) and other factors on preweaning average daily gain (ADG) and weaning weight of beef composites were analysed. Cows with medium or large, well attached udders weaned faster growing and heavier (P , 0.05) calves than cows with small udders or bottle shaped teats with pendulous (BOT) type udders. Cows that were assisted at calving, weaned calves that grew 7.5% slower (P , 0.05) preweaning and were 13.2 kg lighter (P , 0.05) at weaning compared to calves from unassisted cows. Compared to the weaning weights of calves from unassisted cows with BOT type udders, cows with light pull calves and BOT type udders weaned calves that were 26.2 kg lighter, and assisted cows with BOT udders weaned calves that were 26.7 kg lighter at weaning. The decreases (P , 0.05) between assisted and unassisted calves in beef synthetic 1 (BS), BS2 and dairy beef synthetic (DBS) were 9.8, 8.0 and 5.1%, respectively, for preweaning ADG and 8.2, 6.6 and 3.4%, respectively, for weaning weight. The DBS appeared to compensate for the set back of a difficult calving by providing a better nutritional environment for calves than the beef composites. Visual scoring of udders at calving is a practical method of estimating milking ability of and can be used as a tool to cull inefficient cows. 2002 Elsevier Science B.V. All rights reserved. Keywords: Udder type; Calving assistance; Weaning weight; Preweaning average daily gain; Beef composite
1. Introduction Calf preweaning average daily gain and weaning weight are important traits in cow–calf production. *Corresponding author. Tel.: 1 1-780-427-4545; fax: 1 1-780427-1057. E-mail address: [email protected] (L.A. Goonewardene).
In commercial cow–calf systems, where weaned calves are sold, heavier calf weights usually generate more income for producers. Selection for high preweaning gain can improve weaning weight as a moderately correlated response (Burfening et al., 1978) and selection for high birth weight is also effective in increasing weaning weight (Christian et al., 1965; Rutledge et al., 1971). However, the latter is not practiced as high birth weights are also
0301-6226 / 02 / $ – see front matter 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S0301-6226(02)00194-X
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positively correlated with dystocia (Basarab et al., 1993). There are many studies identifying cow and calf factors influencing preweaning average daily gain and weaning weight in beef cattle (Christian et al., 1965; Reynolds et al., 1978; Kress et al., 1995). An important determinant of calf weaning weight is the milk production of the dam (Rutledge et al., 1971) and a few studies in beef cattle have shown that udder capacity, and the size and shape of teats are correlated with the dam’s milk production and calf weaning weight (Frisch, 1982; DeNise et al., 1987). In dairy cattle, it is well established that udder size and certain udder characteristics are positively associated with milk production (White and Vinson, 1975). Some scoring systems have been developed to characterize the udders of beef cattle but little information is available to establish the usefulness of these scoring systems in practical situations. Furthermore, the interactions of factors such as the breed of dam, the degree of calving difficulty, sex of calf and the age of dam, with udder type have not been reported in the literature for calf weaning traits. The objective of this study was to determine the effects of udder type and calving assistance on calf preweaning average daily gain and weaning weight in beef 3 beef and dairy 3 beef composites.
2. Materials and methods The data for the study were obtained from records kept at the University of Alberta Beef Research Station in Kinsella, Alberta, Canada. The data from 1970 to 1995 were used for the analysis of preweaning average daily gain and weaning weight (n 5 10,314). Animals used in the study were cared for in accordance with the Canadian Council of Animal Care (1993) guidelines. The three composites studied were: Beef Synthetic 1 (BS1), Beef Synthetic 2 (BS2) and Dairy Beef Synthetic (DBS). The breed composition of the composite (synthetic) lines and management practices were described by Berg et al. (1990). Briefly, the BS1 is composed of about 33% each of Angus and Charolais, about 20% Galloway, with the remainder comprised of other beef breeds, while the BS2 is made up of approximately 60% Hereford and 40% other beef breeds. The DBS is composed of approximately 60% dairy breeds (Holstein, Brown
Swiss or Simmental) and approximately 40% beef breeds. The Kinsella Research Station which is located in east central Alberta is managed as a commercial unit. The annual precipitation is around 48 cm. Winters in this part of Alberta persist to the end of March, and April snowstorms often occur. All cattle were maintained and managed similarly, and were selected for the same traits. In the early years, selection of breeding sires within each group was based primarily on pre- and post-weaning gain. After 1980, sires with excessively large birth weights were removed from the selection pool. Cows and heifers were bred in single sire breeding groups until 1985 and subsequently in multiple sire breeding groups within each breed group on pasture. The breeding period was approximately 60–80 days. Bred females were pregnancy checked 4 months after exposure to breeding. Heifers and cows failing to wean a calf in any year were culled. Cows with extremely small udders and those with udder problems such as mastitis were culled at weaning time and this accounted for 7.7% of all cows culled. Cows that were given any assistance at calving were culled while heifers that needed a mechanical device, veterinary assistance or Caesarian section were culled. Of the cows culled from the herd, 51.3% were culled for failure to conceive, 12.1% for calf loss, 10.9% for calving problems, 7.7% for udder defects and 9.2% for other problems (Arthur et al., 1992). The breeding herds grazed a mixture of native rough fescue and improved pastures year round and were supplemented with an alfalfa-brome hay and green feed (oats) during the winter, and were supplemented with about 35 kg of roughage (either hay, straw or cereal greenfeed) and about 14 kg of grain (various combinations of barley and oats) per week during the winter (December to March). The actual amounts fed depended upon the severity of the winter, and the weight and condition of the cows. Cows were wintered on open range pastures which were either minimally grazed or not grazed in the previous summer. The pastures contained poplar bluff shelters. Winter supplementation usually began in December and continued through to March. Cows and heifers on the range were given minerals free choice and straw provided for bedding, some of which was eaten. Cows calved in the open range and heifers calved
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out in a separate pasture which was easily accessible. At calving, calf birth weight, cow weight and cow body condition score were recorded. Cow udder types were scored visually as soon after calving as possible. They were grouped into five easily distinguishable classes: small, medium, large and extra large, well attached udders (SWA, MWA, LWA and XLWA), respectively, and bottle-shaped pendulous (defective) udders (BOT). The first four classes were reserved for udders which were held close to the body, with the size category being determined relative to the norms for cattle on this ranch. The BOT category was introduced as a catch-all for the various defects (bottle-shaped teats, poorly attached and pendulous udders) which would result in the cow being culled after weaning. The last udder category was considered a poor udder type. The cows’ mammary system was scored by two individuals with considerable overlap during the 26 year study period. Dystocia was scored on a scale of 0–5, where 0 5 no difficulty, 1 5 light pull (slight assistance), 2 5 puller used (light), 3 5 puller used (hard), 4 5 veterinary assistance required and 5 5 caesarian section (Naazi et al., 1989). For statistical analysis, three calving assistance (CA) classifications were created, no assistance (score 5 0), light pull (score 5 1) and assisted (scores 5 2, 3, 4 or 5). Calves were weaned on 1 day each year usually in September or October. At weaning, the cows weight and body condition score (Lowman et al., 1976) were recorded along with the calf’s weaning weight, and preweaning average daily gain calculated from birth to weaning. Calf preweaning ADG and weaning weight were analyzed by General Linear Model of the Statistical Analysis System (SAS) Institute (SAS, 1985). The effects in the model were udder type (SWA, MWA, LWA, XLWA, BOT), CA (no-assist, light pull, assisted), year of birth (1970–1995), age of dam (2 year heifer, 3–4, 5–6, 7 1 year), breed group (BS1, BS2, DBS), sex of calf (male and female), and all two-way interactions of udder type and CA with the other main effects. Birth weight and weaning age were included as covariates in the model. Least square means (LSM) were compared using the pdiff option of SAS (1985) and done only when the F statistic was significant (P , 0.05). As cow body condition score at calving was only assessed from 1985, its effect on preweaning ADG and weaning
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weight was tested on 3678 observations and found to be not significant (P . 0.10).
3. Results The main effects of year, udder type, calving assistance, age of dam, breed group, sex of calf and interactions of udder type and calving assistance with other main effects, udder type 3 calving assistance, udder type 3 age of dam, calving assistance 3 age of dam, calving assitance 3 breed group, calving assistance 3 sex of calf, udder type 3 year and calving assistance 3 year were significant (P , 0.05) for preweaning ADG and weaning weight. The least square means for preweaning ADG and weaning weight by udder type, calving assistance, age of dam, breed group and sex of calf are shown in Table 1. Cows with SWA, MWA, LWA, XLWA and BOT type udder types accounted for 32.8, 46.7, 14.7, 4.5 and 1.3%, respectively, of all cows sampled. The distribution of cows represented in each udder type by age of dam group is shown in Fig. 1. Ninety two percent of the heifers calving for the first time had either SWA or MWA udders. Among the 3–4-yearold cows, 80% had either SWA or MWA udders and this decreased to 71% among 5–6-year-old cows. Among cows that were 7 years or greater, 73% had either MWA or LWA udder types and 9% had either XLWA or BOT type udders. The proportion of cows with SWA udders decreased from 44% in heifers to 8% in 7 1 year-old cows. Based on main effects (Table 1), cows with medium and large well attached udders weaned faster growing and heavier calves compared to calves from cows with small well attached udders and those with bottle teats and pendulous udders (P , 0.05). However, the interaction of udder type 3 CA for preweaning ADG and weaning weight (Table 2) was significant (P , 0.05). Cows with bottle teats and pendulous udders that were either in the light pull or assisted categories weaned calves that had lower preweaning ADG and weaning weights whereas, unassisted cows even though they had BOT type udders weaned calves that had similar preweaning ADG and weaning weights to those calves from cows with small, medium, large or extra large udders. Thus the presence of a BOT type udder and an assisted birth jointly depressed preweaning
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Table 1 Least-square means for preweaning average daily gain and weaning weight by cow and calf factors Effect
Level
n
Prewean ADG (kg day 21 )
Weaning wt. (kg)
Udder type
SWA MWA LWA XLWA BOT
3382 4821 1513 467 131
1.0160.01 b 1.0460.01 cd 1.0560.01 d 1.0360.02 bc 0.9660.03 a
201.561.3 b 206.861.2 cd 208.261.7 d 205.162.8 bc 192.664.2 a
Calving assistance
No-assist Light pull Assisted
9146 491 677
1.0660.004 a 1.0160.02 b 0.9860.02 b
209.760.6 a 202.362.7 b 196.563.0 b
Age of dam (years)
2 (heifer) 3–4 5–6 71
2823 3490 2452 1549
0.9660.01 a 1.0060.01 b 1.0360.01 bc 1.0760.02 c
192.561.4 a 201.361.8 b 205.662.2 bc 211.963.7 c
Breed group
BS1 BS2 DBS
4137 3935 2242
1.0060.01 a 0.9760.01 b 1.0760.01 c
200.661.5 a 196.161.5 b 211.861.6 c
Sex of calf
Male Female
5340 4974
1.0460.01 a 1.0060.01 b
206.461.4 a 199.361.5 b
ADG5average daily gain. For udder types: SWA5small well attached; MWA5medium well attached; LWA5large well attached; XLWA5extra large well attached; BOT5bottle-shaped teats and pendulous udder. For breed group: BS15beef synthetic 1; BS25beef synthetic 2; DBS5dairy beef synthetic. a,b,c Means with different letters within each effect (udder type, calving assistance, age of dam, breed group and sex of calf) are significantly different (P,0.05).
Fig. 1. Distribution of udder type by age of dam.
growth rate and weaning weight of calves more than when they influenced the traits independently. The udder type and age of dam interaction LSM for preweaning ADG and weaning weight are shown in Table 3. The type of the udder affected the weaning weight of calves from heifers and young cows (3–4
years) more than the weaning weights of calves from older cows. Heifers with extra large well attached udders weaned calves that had lower preweaning ADG and weaning weights than calves from cows with extra large udders. Furthermore, calves suckling MWA or LWA udders of heifers had higher prewean-
L. A. Goonewardene et al. / Livestock Production Science 81 (2003) 47–56 Table 2 Least-square means for the interaction between udder type and calving assistance for preweaning average daily gain and weaning weight Udder type
Calving assistance
Prewean ADG (kg day 21 )
Weaning wt (kg)
SWA
No-assist Light pull Assisted
1.0460.00 defg 1.0060.01 bcd 0.9960.01 bc
206.1760.47 defg 199.1662.39 bcd 197.6062.31 bc
MWA
No-assist Light pull Assisted
1.0760.00 gh 1.0460.01 defg 1.0160.01 bcde
210.2060.36 gh 206.1962.28 defg 201.8062.25 bcde
LWA
No-assist Light pull Assisted
1.0960.00 h 1.0360.02 cdefg 1.0260.02 bcdef
213.5860.66 h 205.1563.30 cdefg 203.8263.35 bcdef
No-assist Light pull Assisted
1.0560.01 efgh 1.0560.04 efgh 0.9860.03 b
208.6661.33 efgh 209.5266.09 efgh 197.1465.45 b
XLWA
BOT
No-assist Light pull Assisted
fgh
1.0660.01 0.9160.06 a 0.9060.05 a
Table 3 Least-square means for the interaction of udder type and age of dam for preweaning average daily gain and weaning weight Udder type
Age of dam (years)
Prewean ADG (kg day 21 )
Weaning wt (kg)
SWA
2 (heifer) 3–4 5–6 71
0.9660.01 bcd 1.0060.01 defg 1.0460.02 ghijk 1.0660.02 ijk
192.3760.93 bcd 200.8061.42 defg 206.3662.67 ghijk 208.5262.94 ijk
MWA
2 (heifer) 3–4 5–6 71
0.9960.01 cdef 1.0560.01 hijk 1.0860.02 k 1.0760.02 jk
197.1061.07 cdef 207.6561.34 hijk 231.6362.51 k 211.4162.81 jk
LWA
2 (heifer) 3–4 5–6 71
1.0460.01 ghijk 1.0560.01 hijk 1.0860.02 k 1.0760.02 jk
204.9462.36 ghijk 207.9862.15 hijk 212.7262.94 k 211.7363.26 jk
XLWA
2 (heifer) 3–4 5–6 71
0.9160.04 a 1.0360.02 fghij 1.0660.03 ijk 1.0860.03 k
187.4166.10 a 205.9863.40 fghij 210.9064.40 ijk 214.5664.36 k
BOT
2 (heifer) 3–4 5–6 71
0.9660.04 bcd 0.9560.04 ac 1.0060.04 defg 1.0260.04 efghi
191.5366.05 bcd 193.2566.95 ac 199.2466.70 defg 202.0365.58 efghi
fgh
210.6862.26 184.4668.10 a 183.9668.12 a
For udder type: SWA5small well attached; MWA5medium well attached; LWA5large well attached; XLWA5extra large well attached; BOT5bottle-shaped teats and pendulous udder. ADG5average daily gain. a–h Means with different letters are significant (P,0.05).
ing ADG and weaning weight. As cows became older, those with MWA, LWA or XLWA udders were associated with high preweaning ADG and weaning weights. Some form of calving assistance was required for 11.3% of the dams, of which 42% required a light pull and 58% required a pull using a mechanical device or veterinary assistance. Calves of unassisted cows grew more rapidly (P , 0.01) to weaning and were heavier (P , 0.01) than calves from cows that needed some form of calving assistance (Table 1). The CA and age of dam interaction LSM for preweaning ADG and weaning weight are shown in Table 4. In general, among heifers, 3–4 and 7 1 year cows, preweaning ADG and weaning weight decreased as the degree of assistance needed increased. However, among the 5–6-year-old cows, those needing a light pull weaned calves that had lower preweaning ADG (1.00 kg day 21 ) and weaning weight (200.7 kg) than calves from cows needing a greater degree of assistance. The CA and breed group interaction LSM for preweaning ADG and
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For udder type: SWA5small well attached; MWA5medium well attached; LWA5large well attached; XLWA5extra large well attached; BOT5bottle-shaped teats and pendulous udder. ADG5Average daily gain. a–k Means with different letters are significant (P,0.05). Table 4 Least-square means for the interaction between calving assistance and age of dam for preweaning average daily gain and weaning weight Calving assistance
Age of dam (years)
Prewean ADG (kg day 21 )
Weaning wt. (kg)
No-assist
2 (heifer) 3–4 5–6 71
1.0060.01 bcd 1.0760.01 ef 1.1160.01 f 1.1060.01 f
199.7361.92 bcd 211.0561.09 ef 217.2060.93 f 216.8860.83 f
Light pull
2 (heifer) 3–4 5–6 71
0.9960.02 bc 1.0260.02 cd 1.0060.04 bcd 1.0860.03 ef
197.1063.21 bc 203.9663.41 cd 200.7366.10 bcd 213.5565.24 ef
Assisted
2 (heifer) 3–4 5–6 71
0.9360.02 a 0.9660.02 ab 1.0560.03 de 0.9960.04 bc
187.0362.68 a 194.3963.43 ab 207.7865.08 de 198.5265.81 bc
ADG5average daily gain. Means with different letters are significant (P,0.05).
a–d
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Table 5 Least-square means for the interaction between calving assistance and breed group for preweaning average daily gain and weaning weight Calving assistance
Breed group
Prewean ADG (kg day 21 )
Weaning wt. (kg)
No-assist
BS1 BS2 DBS
1.0760.00 ef 1.0360.00 cde 1.1160.01 f
211.5360.72 ef 204.2360.71 cde 217.9060.81 f
Light pull
BS1 BS2 DBS
1.0260.02 cd 0.9960.02 bc 1.0760.02 ef
202.4863.44 cd 197.4363.24 cd 211.5963.45 ef
Assisted
BS1 BS2 DBS
0.9660.02 ab 0.9460.02 a 1.0460.02 de
192.7962.96 ab 190.7563.02 a 207.2563.34 de
For breed groups: BS15beef synthetic 1; BS25beef synthetic 2; DBS5dairy beef synthetic. ADG5average daily gain. a–f Means with different letters are significant (P,0.05).
weaning weight is shown in Table 5. The BS1 and BS2 cows that were assisted weaned lighter calves compared to those unassisted but the weaning weights of assisted and unassisted DBS calves were similar. The same was true for preweaning ADG. The calving assistance and sex interaction LSM for preweaning ADG and weaning weight are shown in Table 6. The weaning weights of light pull male calves decreased by 11.7 kg compared to unassisted calves whereas, the weaning weights of light pull female calves decreased by 6.2 kg. Heifers weaned calves that had lighter (P , 0.01) preweaning ADG and were lighter (P , 0.01) at weaning than calves from cows (Table 1). Calves of Table 6 Least-square means for the interaction between calving assistance and sex of calf for preweaning average daily gain and weaning weight Calving assistance
Sex of calf
Prewean ADG (kg day 21 )
Weaning wt. (kg)
No-assist
Male Female
1.1060.00 c 1.0460.00 b
215.9360.69 c 206.5060.70 b
Light pull
Male Female
1.0360.02 b 1.0260.02 b
205.2563.01 b 202.4263.31 b
Assisted
Male Female
1.0160.02 b 0.9560.02 a
201.0362.71 b 192.8363.13 a
ADG5average daily gain. Means with different letters are significant (P,0.05).
a–c
DBS had higher preweaning ADG and were heavier at weaning (P , 0.01) than calves from BS1 and BS2, and male calves had higher (P , 0.01) preweaning ADG and were heavier compared to female calves.
4. Discussion An advantage in preweaning ADG and weaning weight was recognized for calves from cows with large and medium sized well attached udders in our study. It has been shown that the udder capacity at calving scored from 1 (small) to 5 (large) was a significant source of the variation in weaning weight, accounting for 3–7%, while udder shape which ranged from balanced—with even quarters to unbalanced and funnel shaped had no effect on calf weaning weight (DeNise et al., 1987). Doornbos et al. (1981) reported positive associations of subjective udder scores at 130 and 150 days post partum with milk yield and calf gain. On the other hand, ‘bottle teats’ have been associated with high calf weaning weights (Frisch, 1982). In our study the cows with bottle teats and pendulous udders weaned calves that grew at a lesser rate and were lighter at weaning, possibly because the calves received less milk from their dams compared to cows with medium, large or extra large well attached udders. Although there is evidence that certain udder types are associated with high milk production, and high milk production is associated with high weaning weights in beef cattle, presently, there is no agreement on an udder scoring system in the beef industry. Calves from assisted (excluding light pull) cows at calving, weaned calves that grew 7.5% slower from birth to weaning and were 13.2 kg lighter at weaning than unassisted cows. This result disagrees with Bolze et al. (1983) who reported an 8.2-kg advantage in weaning weight for calves from assisted heifers. However, Bolze et al. (1983) did not adjust their data for birth weight, and due to a high and positive correlation between birth and weaning weight (Burfening et al., 1978), calves with higher birth weights (which is one reason for dystocia) were also expected to have higher weaning weights. Calves delivered by Caesarean section have been reported to be significantly lighter at weaning com-
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pared to calves born with no assistance, easy pull or hard pull, and Colburn et al. (1997) theorized that Caesarean surgery may have negatively affected milk production in heifers. Also, the genetic correlations between dystocia score and preweaning ADG and dystocia score and weaning weight are reported to be less than 0.05 (Burfening et al., 1978). As our study shows that calving assistance decreases preweaning ADG and calf weaning weight, it identifies potential economic losses to cow–calf producers who sell weaned calves. There is also a relationship between the time when calving assistance was provided and weaning weight, where calves from early assisted cows weaned heavier calves compared to calves from late assisted cows (Bellows et al., 1988). In our study all dams (heifers and cows) were observed at least once a day for any signs of calving difficulty during the calving season. Although the heifers were calved in a pasture that was easily accessible and cows calved on the range there is no reason to believe that heifers would have been deliberately observed more frequently than cows for calving problems. Compared to the weaning weights of unassisted cows with BOT (poor) udders, light pull cows with BOT type udders weaned calves that were 26.2 kg lighter, and assisted cows with BOT type udders weaned calves that were 26.7 kg lighter at weaning (Table 2). As the combined effects of calving assistance and udder type on preweaning ADG and weaning weight is multiplicative, cows that have difficulties at calving and have poor udders should be the first to be considered for culling. Among the cows . 3 years of age, medium, large and extra large were the better udder types as they were usually associated with higher weaning weights (Table 3). Heifers with large sized udders weaned heavier calves compared to heifers with other udder types. Calves from cows with medium, large and extra large well attached udders weaned heavier calves compared to calves from cows with small udders or those with pendulous udders and bottle teats (Table 3). Among the heifers, only 2% either had extra large or bottle teats and pendulous udders, and it may be recommended that such heifers be culled thereby improving herd efficiency. Cows at the Kinsella station are culled each year for poor udder type and must wean a calf each year to remain
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in the herd. As a consequence, among the 3–6-yearold cows only 1.6% had BOT type udders while 4.3% of the 7 1 year-old cows had BOT udders. In dairy cattle, poorly attached pendulous udders have been reported to be prone to mastitis and frequent injury whereas, high, wide and firmly attached udders with good teat placement have been favorably correlated with longevity (Burnside et al., 1963; DeNise et al., 1987). Heifers are known to have more calving problems than older cows (Laster et al., 1973; Smith et al., 1976; Makarechian et al., 1982) and the frequency of dystocia increased with the increase in calf birth weight (Burfening et al., 1978; Colburn et al., 1997). Preweaning ADG and weaning weight decreased more in assisted calves from either younger (less than 4 years) or older (greater than 7 years) cows, but among calves from the 5–6-year-old assisted cows, the decrease in preweaning ADG and calf weaning weight (Table 4) due to dystocia was less. Bellows et al. (1988) reported that whereas preweaning weight gains of late and early assisted heifers were similar (0.73 vs. 0.72 kg day 21 ), calves from early assisted cows gained more than calves from late assisted cows (1.12 vs. 0.92 kg day 21 ). It is therefore speculated that prolonged labor may result in physical exhaustion that may have a physiological effect on the cow, resulting in a depression in milk production (Doornbos et al., 1984; Bellows et al., 1988). Increased preweaning gains and weaning weights have been achieved at Kinsella by including dairy breeds in the maternal lines of beef crossbreds (Gleddie and Berg, 1968; Pahnish et al., 1969; Pang et al., 1998). The decreases in preweaning ADG of assisted calves relative to unassisted calves in BS1, BS2 and DBS were 9.8, 8.0 and 5.1%, respectively (Table 5). The decreases in weaning weights of assisted compared to unassisted calves in BS1, BS2 and DBS were 8.2, 6.6 and 3.4%, respectively. Our study shows that in spite of the set back due to calving difficulty, assisted DBS cows weaned calves that were closer in gain and weight to calves from unassisted DBS cows, possibly due to higher milk production, attributed to the inclusion of the dairy genes in the maternal beef line. Pang et al. (1998) showed that dairy 3 beef composites can be calved later and weaned earlier, as they provide adequate
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nutrition for their calves, thereby achieving higher preweaning ADG and similar weaning weights to early calving–late weaned beef composites. The present study identifies another advantage in using dairy 3 beef composites as maternal lines, as they partly nullify the ill effects of a difficult calving by adding more weight to the calf at weaning. It is recognized that male calves are heavier at weaning and grow faster than females from birth to weaning (Smith et al., 1976; Pang et al., 1998). Thus the feed requirements (milk) and the nutritional demands of males may be somewhat higher than for female calves. We have shown that the preweaning ADG and weaning weights decreased more for assisted and light pull males than for assisted and light pull females, compared to calves from unassisted cows within sex (Table 6). This is probably related to the heavier demands of male calves in combination with the stresses associated with a difficult birth. Preweaning ADG and weaning weights of male calves from light pull cows decreased by 7.3 and 6.4%, respectively, compared to male calves from unassisted cows whereas, in female calves from light pull cows the decreases in preweaning ADG and weaning weight were 3.3 and 3.0%, respectively. In cow–calf production, a cow’s milking ability is judged on the basis of the calf’s average daily gain from birth to weaning. Any early information on the cow which may indicate that she has a poor milk production potential, and may therefore wean a light calf, would be an advantage. The body condition of the cow at calving has been reported to influence milk production in dairy cattle (Pedron et al., 1993), udder capacity (DeNise et al., 1987) and postpartum reproduction in beef cows (Spitzer et al., 1995). However, body condition score prepartun or at calving has been shown to have no effect on 205-day calf weight and weight gain (Laflamme and Connor, 1992; Spitzer et al., 1995; Morrison et al., 1999). Furthermore, if the body condition at calving is around 2.5 and adequate nutrition is provided after calving, reproduction and calf weaning weight may not be negatively affected (Boadi and Price, 1996; Morrison et al., 1999). At the Kinsella station, calving is usually from mid-April to the end of May. In general, cows lose body condition over the winter months and regain it over the summer months when
they graze spring and summer pasture. The average body condition of cows at calving was 2.5, and at calf weaning (October) was 3.0 (Pang et al., 1998). It has been shown that 205-day calf weaning weights can be influenced more by providing high energy levels during lactation than during gestation, provided cows are in average body condition at calving (Houghton et al., 1990). Visual scoring of udders is a useful method of partially predicting the milking capacity of cows, which in turn has a direct impact on preweaning ADG and calf weaning weight. However, some agreement on a simple visual udder scoring system would be useful in assisting producers to identify and cull heifers and cows that have poor milking potential. This study has shown significant interactions of udder type and calving assistance, and udder type and age of dam. The udder scores can now be considered in combination with calving assistance and age of the dam to recognize and cull inefficient cows.
5. Conclusions In addition to the factors such as age of dam, sex of calf and breed that are known to be associated with preweaning gain and weaning weight, this study identifies the interaction of udder type and calving assistance as another factor. Cows with medium and large well attached udders weaned faster growing and heavier calves compared to cows with small well attached udders, and those with bottle teats. The potential reduction in weaning weight of calves from cows with bottle teats and those with small udders compared to those weaned by cows with large udders were 15.6 and 6.7 kg, respectively. Cows needing assistance, weaned calves that grew 7.5% slower from birth to weaning and were 13.2 kg lighter at weaning. Compared to the weaning weights of unassisted cows with bottle shaped teats and pendulous udders, light pull cows with such udders weaned calves that were 26.2 kg lighter, and assisted cows with poor udders weaned calves that were 26.7 kg lighter at weaning. The significant interaction between calving assistance and udder type indicates that the combined effects of the two factors on preweaning average daily gain and weaning weight were more than additive. Among the cows . 3 years
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of age, the preferred udder types were medium, large and extra large as they were usually associated with high preweaning average daily gain and weaning weight. Assisted Beef Synthetic1 cows weaned calves that were 17.2 kg lighter than calves from unassisted Beef Synthetic1 cows, whereas assisted Dairy Beef Synthetic cows weaned calves that were 8.3 kg lighter than calves from unassisted Dairy Beef Synthetic cows. The Dairy Beef Synthetic cows were probably better able to partly compensate for the set back of a difficult calving by providing a better maternal nutritional environment for their growing calves than the beef 3 beef composites. Visual scoring of udders at calving is a practical and useful option that can be used to predict the milking ability of beef cows and consequently the weaning weights of their calves. In combination with factors such as calving assistance and age, udder type could be used as a tool to cull potentially inefficient beef cows.
Acknowledgements The authors wish to thank the staff at the Kinsella Research Station for collecting the data.
References Arthur, P.F., Makarechian, M., Berg, R.T., Weingardt, R., 1992. Reasons for disposal of cows in a purebred Hereford and two multi breed synthetic groups under range conditions. Can. J. Anim. Sci. 72, 751–758. Basarab, J.A., Rutter, L.M., Day, P.A., 1993. The efficacy of predicting dystocia in yearling beef heifers, 1. using ratios of pelvic area to birth weight or pelvic area to heifer height. J. Anim. Sci. 71, 1359–1371. Bellows, R.A., Short, R.E., Staigmiller, R.B., Milmine, W.L., 1988. Effects of induced parturition and early obstetrical assistance in beef cattle. J. Anim. Sci. 66, 1073–1080. Berg, R.T., Makarechian, M., Arthur, P.F., 1990. The University of Alberta beef breeding project after 30 years—A review. University of Alberta Annual Feeders’ Day Report 69, 65–69. Boadi, D., Price, M.A., 1996. The effects of pre-and early postweaning management on reproductive performance of beef cows. Can. J. Anim. Sci. 76, 337–342. Bolze, R.P., Pruitt, R.J., Corah, L.R., 1983. Cause and effect of dystocia in primiparous beef heifers on subsequent reproductive performance and weaning weights of progeny [abstract]. J. Anim. Sci. 57 (Suppl. 1), 384. Burfening, P.J., Kress, D.D., Friedrich, R.L., Vaniman, D.D., 1978.
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Phenotypic and genetic relationships between calving ease, gestation length, birth weight and preweaning growth. J. Anim. Sci. 47, 595–600. Burnside, E.B., McDaniel, B.T., Legates, J.E., 1963. Relationships among udder height, age and milk production. J. Dairy Sci. 46, 157–158. Canadian Council of Animal Care, 1993. Guide To the Care and Use of Experimental Animals, Vol. 1. CCAC, Ottawa, Canada. Christian, L.L., Hauser, E.R., Chapman, A.B., 1965. Association of preweaning and postweaning traits with weaning weight in cattle. J. Anim. Sci. 24, 652–659. Colburn, D.J., Duetscher, G.H., Nielsen, M.K., Adams, D.C., 1997. Effects of sire, dam traits, calf traits and environment on dystocia and subsequent reproduction in two-year-old heifers. J. Anim. Sci. 75, 1452–1460. DeNise, R.S., Kersey, D.E., Lane, A.M., Rundle, V.L., Torabi, M., 1987. Relationships among udder shape, udder capacity, longevity and calf weights. J. Anim. Sci. 65, 366–372. Doornbos, D.E., Anderson, D.C., Kress, D.D., 1981. Milk production, udder size and calf growth in beef cattle. Proc. West. Sect. Am. Soc. Anim. Sci. 32, 317–318. Doornbos, D.E., Bellows, R.A., Burfening, P.J., Knapp, B.W., 1984. Effects of dam age, prepartum nutrition and duration of labor on productivity and postpartum reproduction in beef females. J. Anim. Sci. 59, 1–10. Frisch, J.E., 1982. The use of teat-size measurements or calf weaning weight as an aid to select against teat defects in cattle. Anim. Prod. 32, 127–133. Gleddie, V.M., Berg, R.T., 1968. Milk production in range beef cows and its relationship to calf gains. Can. J. Anim. Sci. 48, 323–333. Houghton, P.L., Lemenager, R.P., Horstman, L.A., Hendrix, K.S., Moss, G.E., 1990. Effects of body composition, pre and postpartum energy level and early weaning on reproductive performance of beef cows and preweaning calf gain. J. Anim. Sci. 68, 1438–1446. Kress, D.D., Doornbos, D.E., Anderson, D.C., Davis, K.C., 1995. Tarentaise and Hereford breed effects on cow calf traits and estimates of individual heterosis. J. Anim. Sci. 73, 2574–2578. Laflamme, L.F., Connor, M.L., 1992. Effect of postpartum nutrition and cow body condition at parturition on subsequent performance of beef cattle. Can. J. Anim. Sci. 72, 843–851. Laster, D.B., Glimp, H.A., Cundiff, L.V., Gregory, K.E., 1973. Factors affecting dystocia and the effects of dystocia on subsequent reproduction in beef cattle. J. Anim. Sci. 36, 695– 705. Lowman, B.G., Scott, N.A., Sommerville, S.H., 1976. Condition Scoring For Cattle. East of Scotland College of Agriculture Bull. No. 6, November. Edinburgh School of Agriculture, Edinburgh, 31 pp. Makarechian, M., Berg, R.T., Weingardt, R., 1982. Factors influencing calving performance in range beef cattle. Can. J. Anim. Sci. 62, 345–352. Morrison, D.G., Spitzer, J.C., Perkins, J.L., 1999. Influence of prepartum body condition score change on reproduction in multiparous beef cows calving in moderate body condition. J. Anim. Sci. 77, 1048–1054.
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Naazi, A., Makarechian, M., Berg, R.T., 1989. Factors influencing calving difficulty in beef heifers. J. Anim. Sci. 67, 3243–3249. Pahnish, O.F., Brinks, J.S., Urick, J.J., Knapp, B.W., Riley, T.M., 1969. Results from crossing beef 3 beef and beef 3 dairy breeds, calf performance to weaning. J. Anim. Sci. 28, 291– 299. Pang, H., Makarechian, M., Goonewardene, L.A., Berg, R.T., 1998. Effects of early versus late spring calving on beef cow productivity. Can. J. Anim. Sci. 78, 249–255. Pedron, O., Cheli, F., Senatore, E., Baroli, D., Rizzi, R., 1993. Effect of body condition score at calving on performance, some blood parameters, and milk fatty acid composition in dairy cows. J. Dairy Sci. 76, 2528–2535. Reynolds, W.L., DeRouen, T.M., Bellows, R.A., 1978. Relationship of milk yield of dam to early growth of straightbred and crossbred calves. J. Anim. Sci. 47, 584–594.
Rutledge, J.J., Robinson, O.W., Aclschwede, W.T., Legates, J.E., 1971. Milk yield and its influence on 205-day weight of beef calves. J. Anim. Sci. 33, 563–567. SAS, 1985. SAS User’s Guide: Statistics, Ver. 5. SAS Institute Inc, Cary, NC. Smith, G.M., Laster, D.B., Gregory, K.E., 1976. Characterization of biological types of cattle. 1. Dystocia and preweaning growth. J. Anim. Sci. 43, 27–36. Spitzer, J.C., Morrison, D.G., Wettemann, R.P., Faulkner, L.C., 1995. Reproductive responses and calf birth and weaning weights as affected by body condition at parturition and postpartum weight gain in primiparous beef cows. J. Anim. Sci. 73, 1251–1257. White, J.M., Vinson, W.E., 1975. Relationships among udder characteristic, milk yield and non yield traits. J. Dairy Sci. 58, 729–738.
Effect of udder type and calving assistance on weaning traits of beef and dairy 3 beef calves a, a b c b L.A. Goonewardene *, Z. Wang , M.A. Price , R.-C. Yang , R.T. Berg , b M. Makarechian a
Livestock Development Division, Alberta Agriculture, Food and Rural Development, 204 7000 -113 Street, Edmonton, Alberta, Canada T6 H 5 T6 b Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6 G 2 P5 c Research Division, Alberta Agriculture, Food and Rural Development, 202 7000 -113 Street, Edmonton, Alberta, Canada T6 H 5 T6 Received 15 March 2002; received in revised form 5 September 2002; accepted 16 September 2002
Abstract The effects of udder type, calving assistance (CA) and other factors on preweaning average daily gain (ADG) and weaning weight of beef composites were analysed. Cows with medium or large, well attached udders weaned faster growing and heavier (P , 0.05) calves than cows with small udders or bottle shaped teats with pendulous (BOT) type udders. Cows that were assisted at calving, weaned calves that grew 7.5% slower (P , 0.05) preweaning and were 13.2 kg lighter (P , 0.05) at weaning compared to calves from unassisted cows. Compared to the weaning weights of calves from unassisted cows with BOT type udders, cows with light pull calves and BOT type udders weaned calves that were 26.2 kg lighter, and assisted cows with BOT udders weaned calves that were 26.7 kg lighter at weaning. The decreases (P , 0.05) between assisted and unassisted calves in beef synthetic 1 (BS), BS2 and dairy beef synthetic (DBS) were 9.8, 8.0 and 5.1%, respectively, for preweaning ADG and 8.2, 6.6 and 3.4%, respectively, for weaning weight. The DBS appeared to compensate for the set back of a difficult calving by providing a better nutritional environment for calves than the beef composites. Visual scoring of udders at calving is a practical method of estimating milking ability of and can be used as a tool to cull inefficient cows. 2002 Elsevier Science B.V. All rights reserved. Keywords: Udder type; Calving assistance; Weaning weight; Preweaning average daily gain; Beef composite
1. Introduction Calf preweaning average daily gain and weaning weight are important traits in cow–calf production. *Corresponding author. Tel.: 1 1-780-427-4545; fax: 1 1-780427-1057. E-mail address: [email protected] (L.A. Goonewardene).
In commercial cow–calf systems, where weaned calves are sold, heavier calf weights usually generate more income for producers. Selection for high preweaning gain can improve weaning weight as a moderately correlated response (Burfening et al., 1978) and selection for high birth weight is also effective in increasing weaning weight (Christian et al., 1965; Rutledge et al., 1971). However, the latter is not practiced as high birth weights are also
0301-6226 / 02 / $ – see front matter 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S0301-6226(02)00194-X
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positively correlated with dystocia (Basarab et al., 1993). There are many studies identifying cow and calf factors influencing preweaning average daily gain and weaning weight in beef cattle (Christian et al., 1965; Reynolds et al., 1978; Kress et al., 1995). An important determinant of calf weaning weight is the milk production of the dam (Rutledge et al., 1971) and a few studies in beef cattle have shown that udder capacity, and the size and shape of teats are correlated with the dam’s milk production and calf weaning weight (Frisch, 1982; DeNise et al., 1987). In dairy cattle, it is well established that udder size and certain udder characteristics are positively associated with milk production (White and Vinson, 1975). Some scoring systems have been developed to characterize the udders of beef cattle but little information is available to establish the usefulness of these scoring systems in practical situations. Furthermore, the interactions of factors such as the breed of dam, the degree of calving difficulty, sex of calf and the age of dam, with udder type have not been reported in the literature for calf weaning traits. The objective of this study was to determine the effects of udder type and calving assistance on calf preweaning average daily gain and weaning weight in beef 3 beef and dairy 3 beef composites.
2. Materials and methods The data for the study were obtained from records kept at the University of Alberta Beef Research Station in Kinsella, Alberta, Canada. The data from 1970 to 1995 were used for the analysis of preweaning average daily gain and weaning weight (n 5 10,314). Animals used in the study were cared for in accordance with the Canadian Council of Animal Care (1993) guidelines. The three composites studied were: Beef Synthetic 1 (BS1), Beef Synthetic 2 (BS2) and Dairy Beef Synthetic (DBS). The breed composition of the composite (synthetic) lines and management practices were described by Berg et al. (1990). Briefly, the BS1 is composed of about 33% each of Angus and Charolais, about 20% Galloway, with the remainder comprised of other beef breeds, while the BS2 is made up of approximately 60% Hereford and 40% other beef breeds. The DBS is composed of approximately 60% dairy breeds (Holstein, Brown
Swiss or Simmental) and approximately 40% beef breeds. The Kinsella Research Station which is located in east central Alberta is managed as a commercial unit. The annual precipitation is around 48 cm. Winters in this part of Alberta persist to the end of March, and April snowstorms often occur. All cattle were maintained and managed similarly, and were selected for the same traits. In the early years, selection of breeding sires within each group was based primarily on pre- and post-weaning gain. After 1980, sires with excessively large birth weights were removed from the selection pool. Cows and heifers were bred in single sire breeding groups until 1985 and subsequently in multiple sire breeding groups within each breed group on pasture. The breeding period was approximately 60–80 days. Bred females were pregnancy checked 4 months after exposure to breeding. Heifers and cows failing to wean a calf in any year were culled. Cows with extremely small udders and those with udder problems such as mastitis were culled at weaning time and this accounted for 7.7% of all cows culled. Cows that were given any assistance at calving were culled while heifers that needed a mechanical device, veterinary assistance or Caesarian section were culled. Of the cows culled from the herd, 51.3% were culled for failure to conceive, 12.1% for calf loss, 10.9% for calving problems, 7.7% for udder defects and 9.2% for other problems (Arthur et al., 1992). The breeding herds grazed a mixture of native rough fescue and improved pastures year round and were supplemented with an alfalfa-brome hay and green feed (oats) during the winter, and were supplemented with about 35 kg of roughage (either hay, straw or cereal greenfeed) and about 14 kg of grain (various combinations of barley and oats) per week during the winter (December to March). The actual amounts fed depended upon the severity of the winter, and the weight and condition of the cows. Cows were wintered on open range pastures which were either minimally grazed or not grazed in the previous summer. The pastures contained poplar bluff shelters. Winter supplementation usually began in December and continued through to March. Cows and heifers on the range were given minerals free choice and straw provided for bedding, some of which was eaten. Cows calved in the open range and heifers calved
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out in a separate pasture which was easily accessible. At calving, calf birth weight, cow weight and cow body condition score were recorded. Cow udder types were scored visually as soon after calving as possible. They were grouped into five easily distinguishable classes: small, medium, large and extra large, well attached udders (SWA, MWA, LWA and XLWA), respectively, and bottle-shaped pendulous (defective) udders (BOT). The first four classes were reserved for udders which were held close to the body, with the size category being determined relative to the norms for cattle on this ranch. The BOT category was introduced as a catch-all for the various defects (bottle-shaped teats, poorly attached and pendulous udders) which would result in the cow being culled after weaning. The last udder category was considered a poor udder type. The cows’ mammary system was scored by two individuals with considerable overlap during the 26 year study period. Dystocia was scored on a scale of 0–5, where 0 5 no difficulty, 1 5 light pull (slight assistance), 2 5 puller used (light), 3 5 puller used (hard), 4 5 veterinary assistance required and 5 5 caesarian section (Naazi et al., 1989). For statistical analysis, three calving assistance (CA) classifications were created, no assistance (score 5 0), light pull (score 5 1) and assisted (scores 5 2, 3, 4 or 5). Calves were weaned on 1 day each year usually in September or October. At weaning, the cows weight and body condition score (Lowman et al., 1976) were recorded along with the calf’s weaning weight, and preweaning average daily gain calculated from birth to weaning. Calf preweaning ADG and weaning weight were analyzed by General Linear Model of the Statistical Analysis System (SAS) Institute (SAS, 1985). The effects in the model were udder type (SWA, MWA, LWA, XLWA, BOT), CA (no-assist, light pull, assisted), year of birth (1970–1995), age of dam (2 year heifer, 3–4, 5–6, 7 1 year), breed group (BS1, BS2, DBS), sex of calf (male and female), and all two-way interactions of udder type and CA with the other main effects. Birth weight and weaning age were included as covariates in the model. Least square means (LSM) were compared using the pdiff option of SAS (1985) and done only when the F statistic was significant (P , 0.05). As cow body condition score at calving was only assessed from 1985, its effect on preweaning ADG and weaning
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weight was tested on 3678 observations and found to be not significant (P . 0.10).
3. Results The main effects of year, udder type, calving assistance, age of dam, breed group, sex of calf and interactions of udder type and calving assistance with other main effects, udder type 3 calving assistance, udder type 3 age of dam, calving assistance 3 age of dam, calving assitance 3 breed group, calving assistance 3 sex of calf, udder type 3 year and calving assistance 3 year were significant (P , 0.05) for preweaning ADG and weaning weight. The least square means for preweaning ADG and weaning weight by udder type, calving assistance, age of dam, breed group and sex of calf are shown in Table 1. Cows with SWA, MWA, LWA, XLWA and BOT type udder types accounted for 32.8, 46.7, 14.7, 4.5 and 1.3%, respectively, of all cows sampled. The distribution of cows represented in each udder type by age of dam group is shown in Fig. 1. Ninety two percent of the heifers calving for the first time had either SWA or MWA udders. Among the 3–4-yearold cows, 80% had either SWA or MWA udders and this decreased to 71% among 5–6-year-old cows. Among cows that were 7 years or greater, 73% had either MWA or LWA udder types and 9% had either XLWA or BOT type udders. The proportion of cows with SWA udders decreased from 44% in heifers to 8% in 7 1 year-old cows. Based on main effects (Table 1), cows with medium and large well attached udders weaned faster growing and heavier calves compared to calves from cows with small well attached udders and those with bottle teats and pendulous udders (P , 0.05). However, the interaction of udder type 3 CA for preweaning ADG and weaning weight (Table 2) was significant (P , 0.05). Cows with bottle teats and pendulous udders that were either in the light pull or assisted categories weaned calves that had lower preweaning ADG and weaning weights whereas, unassisted cows even though they had BOT type udders weaned calves that had similar preweaning ADG and weaning weights to those calves from cows with small, medium, large or extra large udders. Thus the presence of a BOT type udder and an assisted birth jointly depressed preweaning
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Table 1 Least-square means for preweaning average daily gain and weaning weight by cow and calf factors Effect
Level
n
Prewean ADG (kg day 21 )
Weaning wt. (kg)
Udder type
SWA MWA LWA XLWA BOT
3382 4821 1513 467 131
1.0160.01 b 1.0460.01 cd 1.0560.01 d 1.0360.02 bc 0.9660.03 a
201.561.3 b 206.861.2 cd 208.261.7 d 205.162.8 bc 192.664.2 a
Calving assistance
No-assist Light pull Assisted
9146 491 677
1.0660.004 a 1.0160.02 b 0.9860.02 b
209.760.6 a 202.362.7 b 196.563.0 b
Age of dam (years)
2 (heifer) 3–4 5–6 71
2823 3490 2452 1549
0.9660.01 a 1.0060.01 b 1.0360.01 bc 1.0760.02 c
192.561.4 a 201.361.8 b 205.662.2 bc 211.963.7 c
Breed group
BS1 BS2 DBS
4137 3935 2242
1.0060.01 a 0.9760.01 b 1.0760.01 c
200.661.5 a 196.161.5 b 211.861.6 c
Sex of calf
Male Female
5340 4974
1.0460.01 a 1.0060.01 b
206.461.4 a 199.361.5 b
ADG5average daily gain. For udder types: SWA5small well attached; MWA5medium well attached; LWA5large well attached; XLWA5extra large well attached; BOT5bottle-shaped teats and pendulous udder. For breed group: BS15beef synthetic 1; BS25beef synthetic 2; DBS5dairy beef synthetic. a,b,c Means with different letters within each effect (udder type, calving assistance, age of dam, breed group and sex of calf) are significantly different (P,0.05).
Fig. 1. Distribution of udder type by age of dam.
growth rate and weaning weight of calves more than when they influenced the traits independently. The udder type and age of dam interaction LSM for preweaning ADG and weaning weight are shown in Table 3. The type of the udder affected the weaning weight of calves from heifers and young cows (3–4
years) more than the weaning weights of calves from older cows. Heifers with extra large well attached udders weaned calves that had lower preweaning ADG and weaning weights than calves from cows with extra large udders. Furthermore, calves suckling MWA or LWA udders of heifers had higher prewean-
L. A. Goonewardene et al. / Livestock Production Science 81 (2003) 47–56 Table 2 Least-square means for the interaction between udder type and calving assistance for preweaning average daily gain and weaning weight Udder type
Calving assistance
Prewean ADG (kg day 21 )
Weaning wt (kg)
SWA
No-assist Light pull Assisted
1.0460.00 defg 1.0060.01 bcd 0.9960.01 bc
206.1760.47 defg 199.1662.39 bcd 197.6062.31 bc
MWA
No-assist Light pull Assisted
1.0760.00 gh 1.0460.01 defg 1.0160.01 bcde
210.2060.36 gh 206.1962.28 defg 201.8062.25 bcde
LWA
No-assist Light pull Assisted
1.0960.00 h 1.0360.02 cdefg 1.0260.02 bcdef
213.5860.66 h 205.1563.30 cdefg 203.8263.35 bcdef
No-assist Light pull Assisted
1.0560.01 efgh 1.0560.04 efgh 0.9860.03 b
208.6661.33 efgh 209.5266.09 efgh 197.1465.45 b
XLWA
BOT
No-assist Light pull Assisted
fgh
1.0660.01 0.9160.06 a 0.9060.05 a
Table 3 Least-square means for the interaction of udder type and age of dam for preweaning average daily gain and weaning weight Udder type
Age of dam (years)
Prewean ADG (kg day 21 )
Weaning wt (kg)
SWA
2 (heifer) 3–4 5–6 71
0.9660.01 bcd 1.0060.01 defg 1.0460.02 ghijk 1.0660.02 ijk
192.3760.93 bcd 200.8061.42 defg 206.3662.67 ghijk 208.5262.94 ijk
MWA
2 (heifer) 3–4 5–6 71
0.9960.01 cdef 1.0560.01 hijk 1.0860.02 k 1.0760.02 jk
197.1061.07 cdef 207.6561.34 hijk 231.6362.51 k 211.4162.81 jk
LWA
2 (heifer) 3–4 5–6 71
1.0460.01 ghijk 1.0560.01 hijk 1.0860.02 k 1.0760.02 jk
204.9462.36 ghijk 207.9862.15 hijk 212.7262.94 k 211.7363.26 jk
XLWA
2 (heifer) 3–4 5–6 71
0.9160.04 a 1.0360.02 fghij 1.0660.03 ijk 1.0860.03 k
187.4166.10 a 205.9863.40 fghij 210.9064.40 ijk 214.5664.36 k
BOT
2 (heifer) 3–4 5–6 71
0.9660.04 bcd 0.9560.04 ac 1.0060.04 defg 1.0260.04 efghi
191.5366.05 bcd 193.2566.95 ac 199.2466.70 defg 202.0365.58 efghi
fgh
210.6862.26 184.4668.10 a 183.9668.12 a
For udder type: SWA5small well attached; MWA5medium well attached; LWA5large well attached; XLWA5extra large well attached; BOT5bottle-shaped teats and pendulous udder. ADG5average daily gain. a–h Means with different letters are significant (P,0.05).
ing ADG and weaning weight. As cows became older, those with MWA, LWA or XLWA udders were associated with high preweaning ADG and weaning weights. Some form of calving assistance was required for 11.3% of the dams, of which 42% required a light pull and 58% required a pull using a mechanical device or veterinary assistance. Calves of unassisted cows grew more rapidly (P , 0.01) to weaning and were heavier (P , 0.01) than calves from cows that needed some form of calving assistance (Table 1). The CA and age of dam interaction LSM for preweaning ADG and weaning weight are shown in Table 4. In general, among heifers, 3–4 and 7 1 year cows, preweaning ADG and weaning weight decreased as the degree of assistance needed increased. However, among the 5–6-year-old cows, those needing a light pull weaned calves that had lower preweaning ADG (1.00 kg day 21 ) and weaning weight (200.7 kg) than calves from cows needing a greater degree of assistance. The CA and breed group interaction LSM for preweaning ADG and
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For udder type: SWA5small well attached; MWA5medium well attached; LWA5large well attached; XLWA5extra large well attached; BOT5bottle-shaped teats and pendulous udder. ADG5Average daily gain. a–k Means with different letters are significant (P,0.05). Table 4 Least-square means for the interaction between calving assistance and age of dam for preweaning average daily gain and weaning weight Calving assistance
Age of dam (years)
Prewean ADG (kg day 21 )
Weaning wt. (kg)
No-assist
2 (heifer) 3–4 5–6 71
1.0060.01 bcd 1.0760.01 ef 1.1160.01 f 1.1060.01 f
199.7361.92 bcd 211.0561.09 ef 217.2060.93 f 216.8860.83 f
Light pull
2 (heifer) 3–4 5–6 71
0.9960.02 bc 1.0260.02 cd 1.0060.04 bcd 1.0860.03 ef
197.1063.21 bc 203.9663.41 cd 200.7366.10 bcd 213.5565.24 ef
Assisted
2 (heifer) 3–4 5–6 71
0.9360.02 a 0.9660.02 ab 1.0560.03 de 0.9960.04 bc
187.0362.68 a 194.3963.43 ab 207.7865.08 de 198.5265.81 bc
ADG5average daily gain. Means with different letters are significant (P,0.05).
a–d
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Table 5 Least-square means for the interaction between calving assistance and breed group for preweaning average daily gain and weaning weight Calving assistance
Breed group
Prewean ADG (kg day 21 )
Weaning wt. (kg)
No-assist
BS1 BS2 DBS
1.0760.00 ef 1.0360.00 cde 1.1160.01 f
211.5360.72 ef 204.2360.71 cde 217.9060.81 f
Light pull
BS1 BS2 DBS
1.0260.02 cd 0.9960.02 bc 1.0760.02 ef
202.4863.44 cd 197.4363.24 cd 211.5963.45 ef
Assisted
BS1 BS2 DBS
0.9660.02 ab 0.9460.02 a 1.0460.02 de
192.7962.96 ab 190.7563.02 a 207.2563.34 de
For breed groups: BS15beef synthetic 1; BS25beef synthetic 2; DBS5dairy beef synthetic. ADG5average daily gain. a–f Means with different letters are significant (P,0.05).
weaning weight is shown in Table 5. The BS1 and BS2 cows that were assisted weaned lighter calves compared to those unassisted but the weaning weights of assisted and unassisted DBS calves were similar. The same was true for preweaning ADG. The calving assistance and sex interaction LSM for preweaning ADG and weaning weight are shown in Table 6. The weaning weights of light pull male calves decreased by 11.7 kg compared to unassisted calves whereas, the weaning weights of light pull female calves decreased by 6.2 kg. Heifers weaned calves that had lighter (P , 0.01) preweaning ADG and were lighter (P , 0.01) at weaning than calves from cows (Table 1). Calves of Table 6 Least-square means for the interaction between calving assistance and sex of calf for preweaning average daily gain and weaning weight Calving assistance
Sex of calf
Prewean ADG (kg day 21 )
Weaning wt. (kg)
No-assist
Male Female
1.1060.00 c 1.0460.00 b
215.9360.69 c 206.5060.70 b
Light pull
Male Female
1.0360.02 b 1.0260.02 b
205.2563.01 b 202.4263.31 b
Assisted
Male Female
1.0160.02 b 0.9560.02 a
201.0362.71 b 192.8363.13 a
ADG5average daily gain. Means with different letters are significant (P,0.05).
a–c
DBS had higher preweaning ADG and were heavier at weaning (P , 0.01) than calves from BS1 and BS2, and male calves had higher (P , 0.01) preweaning ADG and were heavier compared to female calves.
4. Discussion An advantage in preweaning ADG and weaning weight was recognized for calves from cows with large and medium sized well attached udders in our study. It has been shown that the udder capacity at calving scored from 1 (small) to 5 (large) was a significant source of the variation in weaning weight, accounting for 3–7%, while udder shape which ranged from balanced—with even quarters to unbalanced and funnel shaped had no effect on calf weaning weight (DeNise et al., 1987). Doornbos et al. (1981) reported positive associations of subjective udder scores at 130 and 150 days post partum with milk yield and calf gain. On the other hand, ‘bottle teats’ have been associated with high calf weaning weights (Frisch, 1982). In our study the cows with bottle teats and pendulous udders weaned calves that grew at a lesser rate and were lighter at weaning, possibly because the calves received less milk from their dams compared to cows with medium, large or extra large well attached udders. Although there is evidence that certain udder types are associated with high milk production, and high milk production is associated with high weaning weights in beef cattle, presently, there is no agreement on an udder scoring system in the beef industry. Calves from assisted (excluding light pull) cows at calving, weaned calves that grew 7.5% slower from birth to weaning and were 13.2 kg lighter at weaning than unassisted cows. This result disagrees with Bolze et al. (1983) who reported an 8.2-kg advantage in weaning weight for calves from assisted heifers. However, Bolze et al. (1983) did not adjust their data for birth weight, and due to a high and positive correlation between birth and weaning weight (Burfening et al., 1978), calves with higher birth weights (which is one reason for dystocia) were also expected to have higher weaning weights. Calves delivered by Caesarean section have been reported to be significantly lighter at weaning com-
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pared to calves born with no assistance, easy pull or hard pull, and Colburn et al. (1997) theorized that Caesarean surgery may have negatively affected milk production in heifers. Also, the genetic correlations between dystocia score and preweaning ADG and dystocia score and weaning weight are reported to be less than 0.05 (Burfening et al., 1978). As our study shows that calving assistance decreases preweaning ADG and calf weaning weight, it identifies potential economic losses to cow–calf producers who sell weaned calves. There is also a relationship between the time when calving assistance was provided and weaning weight, where calves from early assisted cows weaned heavier calves compared to calves from late assisted cows (Bellows et al., 1988). In our study all dams (heifers and cows) were observed at least once a day for any signs of calving difficulty during the calving season. Although the heifers were calved in a pasture that was easily accessible and cows calved on the range there is no reason to believe that heifers would have been deliberately observed more frequently than cows for calving problems. Compared to the weaning weights of unassisted cows with BOT (poor) udders, light pull cows with BOT type udders weaned calves that were 26.2 kg lighter, and assisted cows with BOT type udders weaned calves that were 26.7 kg lighter at weaning (Table 2). As the combined effects of calving assistance and udder type on preweaning ADG and weaning weight is multiplicative, cows that have difficulties at calving and have poor udders should be the first to be considered for culling. Among the cows . 3 years of age, medium, large and extra large were the better udder types as they were usually associated with higher weaning weights (Table 3). Heifers with large sized udders weaned heavier calves compared to heifers with other udder types. Calves from cows with medium, large and extra large well attached udders weaned heavier calves compared to calves from cows with small udders or those with pendulous udders and bottle teats (Table 3). Among the heifers, only 2% either had extra large or bottle teats and pendulous udders, and it may be recommended that such heifers be culled thereby improving herd efficiency. Cows at the Kinsella station are culled each year for poor udder type and must wean a calf each year to remain
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in the herd. As a consequence, among the 3–6-yearold cows only 1.6% had BOT type udders while 4.3% of the 7 1 year-old cows had BOT udders. In dairy cattle, poorly attached pendulous udders have been reported to be prone to mastitis and frequent injury whereas, high, wide and firmly attached udders with good teat placement have been favorably correlated with longevity (Burnside et al., 1963; DeNise et al., 1987). Heifers are known to have more calving problems than older cows (Laster et al., 1973; Smith et al., 1976; Makarechian et al., 1982) and the frequency of dystocia increased with the increase in calf birth weight (Burfening et al., 1978; Colburn et al., 1997). Preweaning ADG and weaning weight decreased more in assisted calves from either younger (less than 4 years) or older (greater than 7 years) cows, but among calves from the 5–6-year-old assisted cows, the decrease in preweaning ADG and calf weaning weight (Table 4) due to dystocia was less. Bellows et al. (1988) reported that whereas preweaning weight gains of late and early assisted heifers were similar (0.73 vs. 0.72 kg day 21 ), calves from early assisted cows gained more than calves from late assisted cows (1.12 vs. 0.92 kg day 21 ). It is therefore speculated that prolonged labor may result in physical exhaustion that may have a physiological effect on the cow, resulting in a depression in milk production (Doornbos et al., 1984; Bellows et al., 1988). Increased preweaning gains and weaning weights have been achieved at Kinsella by including dairy breeds in the maternal lines of beef crossbreds (Gleddie and Berg, 1968; Pahnish et al., 1969; Pang et al., 1998). The decreases in preweaning ADG of assisted calves relative to unassisted calves in BS1, BS2 and DBS were 9.8, 8.0 and 5.1%, respectively (Table 5). The decreases in weaning weights of assisted compared to unassisted calves in BS1, BS2 and DBS were 8.2, 6.6 and 3.4%, respectively. Our study shows that in spite of the set back due to calving difficulty, assisted DBS cows weaned calves that were closer in gain and weight to calves from unassisted DBS cows, possibly due to higher milk production, attributed to the inclusion of the dairy genes in the maternal beef line. Pang et al. (1998) showed that dairy 3 beef composites can be calved later and weaned earlier, as they provide adequate
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nutrition for their calves, thereby achieving higher preweaning ADG and similar weaning weights to early calving–late weaned beef composites. The present study identifies another advantage in using dairy 3 beef composites as maternal lines, as they partly nullify the ill effects of a difficult calving by adding more weight to the calf at weaning. It is recognized that male calves are heavier at weaning and grow faster than females from birth to weaning (Smith et al., 1976; Pang et al., 1998). Thus the feed requirements (milk) and the nutritional demands of males may be somewhat higher than for female calves. We have shown that the preweaning ADG and weaning weights decreased more for assisted and light pull males than for assisted and light pull females, compared to calves from unassisted cows within sex (Table 6). This is probably related to the heavier demands of male calves in combination with the stresses associated with a difficult birth. Preweaning ADG and weaning weights of male calves from light pull cows decreased by 7.3 and 6.4%, respectively, compared to male calves from unassisted cows whereas, in female calves from light pull cows the decreases in preweaning ADG and weaning weight were 3.3 and 3.0%, respectively. In cow–calf production, a cow’s milking ability is judged on the basis of the calf’s average daily gain from birth to weaning. Any early information on the cow which may indicate that she has a poor milk production potential, and may therefore wean a light calf, would be an advantage. The body condition of the cow at calving has been reported to influence milk production in dairy cattle (Pedron et al., 1993), udder capacity (DeNise et al., 1987) and postpartum reproduction in beef cows (Spitzer et al., 1995). However, body condition score prepartun or at calving has been shown to have no effect on 205-day calf weight and weight gain (Laflamme and Connor, 1992; Spitzer et al., 1995; Morrison et al., 1999). Furthermore, if the body condition at calving is around 2.5 and adequate nutrition is provided after calving, reproduction and calf weaning weight may not be negatively affected (Boadi and Price, 1996; Morrison et al., 1999). At the Kinsella station, calving is usually from mid-April to the end of May. In general, cows lose body condition over the winter months and regain it over the summer months when
they graze spring and summer pasture. The average body condition of cows at calving was 2.5, and at calf weaning (October) was 3.0 (Pang et al., 1998). It has been shown that 205-day calf weaning weights can be influenced more by providing high energy levels during lactation than during gestation, provided cows are in average body condition at calving (Houghton et al., 1990). Visual scoring of udders is a useful method of partially predicting the milking capacity of cows, which in turn has a direct impact on preweaning ADG and calf weaning weight. However, some agreement on a simple visual udder scoring system would be useful in assisting producers to identify and cull heifers and cows that have poor milking potential. This study has shown significant interactions of udder type and calving assistance, and udder type and age of dam. The udder scores can now be considered in combination with calving assistance and age of the dam to recognize and cull inefficient cows.
5. Conclusions In addition to the factors such as age of dam, sex of calf and breed that are known to be associated with preweaning gain and weaning weight, this study identifies the interaction of udder type and calving assistance as another factor. Cows with medium and large well attached udders weaned faster growing and heavier calves compared to cows with small well attached udders, and those with bottle teats. The potential reduction in weaning weight of calves from cows with bottle teats and those with small udders compared to those weaned by cows with large udders were 15.6 and 6.7 kg, respectively. Cows needing assistance, weaned calves that grew 7.5% slower from birth to weaning and were 13.2 kg lighter at weaning. Compared to the weaning weights of unassisted cows with bottle shaped teats and pendulous udders, light pull cows with such udders weaned calves that were 26.2 kg lighter, and assisted cows with poor udders weaned calves that were 26.7 kg lighter at weaning. The significant interaction between calving assistance and udder type indicates that the combined effects of the two factors on preweaning average daily gain and weaning weight were more than additive. Among the cows . 3 years
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of age, the preferred udder types were medium, large and extra large as they were usually associated with high preweaning average daily gain and weaning weight. Assisted Beef Synthetic1 cows weaned calves that were 17.2 kg lighter than calves from unassisted Beef Synthetic1 cows, whereas assisted Dairy Beef Synthetic cows weaned calves that were 8.3 kg lighter than calves from unassisted Dairy Beef Synthetic cows. The Dairy Beef Synthetic cows were probably better able to partly compensate for the set back of a difficult calving by providing a better maternal nutritional environment for their growing calves than the beef 3 beef composites. Visual scoring of udders at calving is a practical and useful option that can be used to predict the milking ability of beef cows and consequently the weaning weights of their calves. In combination with factors such as calving assistance and age, udder type could be used as a tool to cull potentially inefficient beef cows.
Acknowledgements The authors wish to thank the staff at the Kinsella Research Station for collecting the data.
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