Maternal Body Weight and Feed Allowance of Breeders Affect Performance of Dwarf Broiler Breeders and Tibial Ossification of Their Progeny

Maternal Body Weight and Feed Allowance of Breeders Affect Performance of Dwarf Broiler Breeders and Tibial Ossification of Their Progeny TRIYUWANTA,1 C. LETERRIER, J. P. BRILLARD, and Y. NYS Station de Recherches Avicoles, Institut National de la Recherche Agronomique, 37380 Nouzilly, France (Received for publication March 1, 1991)

1992 Poultry Science 71:244-254

INTRODUCTION 1

Present address: Faculty of Animal Husbandry, Gadjah Mada University, Yogyakarta, Indonesia.

Most commercial broiler breeders are submitted to feed restriction during the rearing and laying phases to reduce breed-

244

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ABSTRACT Four hundred and eight dwarf broiler breeder hens were raised collectively in a floor pen to 21 wk of age. At this age they were classified into four groups with reference to their individual BW as heavy (1.95 ± .1 kg), medium (1.80±.1 kg), light (1.69±.1 kg),and ultralight (1.57±.1 kg). All groups were individually caged at 23 wk of age. During the reproductive period, each group was divided into three subgroups fed on liberal, intermediate, or severe feed restriction (reaching u p to 135,125, and 115 g of daily feed allowance at 29 wk of age, respectively). Intergroup differences in BW were maintained throughout the experiment (21 to 61 wk) but tended to decrease with age. Hen-day egg production was depressed by the lower feed allowance. Fertility and hatchability were impaired when hens received the largest quantities of food. Hen size influenced female breeder performance only slightly. Shell quality and albumen quality were affected by the level of feed consumption. Egg weights as well as BW of the progeny at hatching were enhanced by increased maternal BW and feed allowance. This positive maternal effect was still present at 40 days of age. Despite better overall BW performances of the male versus female broilers, the abdominal fat pad of female broilers was heavier than that of males and tended to increase with breeder size and breeder feed allowance. Accordingly, tibial breaking strength and percentage ash of the progeny at hatching were markedly improved in proportion to the breeders' BW and to their feed allowance. The effect of breeder size on broiler tibial quality was maintained u p to 40 days of age but the effect of breeder feed intake tended to disappear with increasing age of the broilers. Tibial strength and mineralization were higher in male than in female broilers at 40 days of age. Dyschondroplasia was higher in broilers hatched from heavier breeder hens, but was not influenced by breeder feed intake. The incidence of varus and valgus in progeny was similar whatever the breeders' treatment. It is concluded that performance of dwarf breeders in a given flock depends mainly upon breeder feed allowance but that broiler performance and, especially, tibial ossification of broilers is greatly influenced by maternal size and, to a lesser extent, by maternal feed intake. (Key words: dwarf breeder hens, body weight, feed restriction, broiler growth, progeny tibial ossification)

BREEDER TREATMENTS AND PROGENY PERFORMANCE

2 Institut de Selection Animale, 1989, 69003 Lyon, France.

few reports, it has been observed that parental nutrition could influence both body growth and the overall development of the embryo (Beer, 1969; Blum et al., 1979). The purposes of the present study were to investigate the consequences of individual BW fluctuations observed in a flock of dwarf broiler breeders after sexual maturity and the influence of various levels of feed restriction within each weight grouping on individual breeder performance, and on body growth, tibial mineralization, and leg abnormalities of the offspring. MATERIALS AND METHODS Four hundred and eight ISA Vedette dwarf broiler breeders 0V15) were hatched in April and reared in floor pens with litter through 21 wk of age according to the breeder's guide recommendations.'' A starter diet (2,980 kcal ME/kg and 19.0% CP) from 0 to 6 wk and a grower diet (2,830 kcal ME/kg and 15.6% CP) from 7 to 21 wk of age were allocated in severely restricted amounts (42 g at 5 wk progressively increased to 70 g at 21 wk). Access to water was unlimited. Birds were submitted to 8 h of light daily from 2 to 21 wk of age. The day length was increased thereafter by 2 h/wk to a maximum of 14 h at 23 wk and maintained up to 61 wk. Hens were individually caged at 23 wk of age. No experimental treatments were provided until 21 wk of age. At this age, hens were divided into four groups based on individual BW. Birds were classified as ultralight (1.57 ± .1 kg), light (1.69 ± .1 kg), medium (1.80 ± .1 kg), and heavy (1.95 ± .1 kg). Within each group, three subgroups (32 hens each) were made and fed either a liberal, an intermediate, or a severe schedule of feed restriction as described in Table 1. Feed allotments were controlled daily. The breeder diet contained 2,810 kcal ME/ kg and 16.5% CP (Table 2). Every 4 wk, the same 10 hens per treatment were weighed. Hen-day production and deaths were recorded daily. Egg quality was measured on three consecutive eggs per hen at 43 and 57 wk of age. Egg weight, Haugh unit, shell weight, and shell index were measured using the EQM

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ing costs and improve the efficiency of broiler chick production. Breeders provided ad libitum access to feed overconsume and become fatty, and their reproductive performances are impaired (McDaniel et al., 1981; Pearson and Herron, 1981; Wilson et al., 1983). Positive effects of restricting breeder hens during the laying period are observed without any detrimental influence on laying performance with feed restrictions of 20% of ad libitum (Pearson and Herron, 1980; Wilson and Harms, 1984; Leclercq, 1986) but egg number decreases at lower intake in the normal broiler breeder (Pym and Dillon, 1974; Blair et al., 1976) or in dwarf breeder hens (Larbier, 1985). Broiler breeders are generally reared on a more severe feed restriction regimen than mature hens in order to reduce BW and to delay sexual maturity and, as a consequence, to improve subsequent performance (Pym and Dillon, 1974; Proudfoot, 1979; Robbins et al., 1986). Quantitative feed restriction during the rearing period may, however, reduce the uniformity of a flock due to competition for feed. Different classes of immature BW at sexual maturity have been associated with changes in hen-day production and egg weight (Leeson and Summers, 1987; Lilburn and Myers-Miller, 1990). Therefore, the question arises of how best to adjust feed intake during the laying period with reference to the initial body weight. On the other hand, broiler breeder BW and feed allowance influence egg weight (McDaniel et al., 1981; Pearson and Herron, 1982). There is a high positive correlation between egg weight and chick weight at hatching (McNaughton et al., 1978; Wyatt et al, 1985; Shanawany, 1987). Chicks hatched from large eggs tend to be heavier at hatching time (Al-Murrani, 1978; Proudfoot and Hulan, 1981). However, reports concerning the parental effects on the carcass composition (Spratt and Leeson, 1987) and on leg problems of the offspring are scarce, especially as far as mineral composition is concerned. In a

245

246

TRIYUWANTA ET AL. TABLE 1. Daily feed intake of broiler breeder hens

TABLE 2. Composition of the diet Ingredients and composition

Age

90 100 105 110 120 130 130 135 132 130 127 125 122 120

Intermediate diet

Severe diet

— (g per hen) 70 78 86 88 90 95 90 100 105 95 1 110 1001 120 1051 125 1151 125 115 122 112 120 110 117 107 115 105 112 102 110 100

lr The ultralight and light groups were fed 10 g more than this indicated value.

system3 for egg quality. The eggshell breaking strength was measured with an Instron testing machine.4 Hens were inseminated at 44 and 58 wk of age on 2 consecutive days with 120 million spermatozoa collected from broiler breeder males (I992). Fertility and hatchability of fertile eggs were determined from the eggs collected for 1 wk starting the 1st day following the second artificial insemination. The offspring produced from 44-wk-old breeders were reared on litter until 40 days of age and fed a diet containing 3,040 kcal ME/kg, 22.1% CP (starter; 0 to 21 days) and 2,980 kcal ME/kg, 19.0% CP (finisher). At 40 days of age, all male chicks were examined for bowed legs and scored for varus and valgus deformations. Birds showing varus angulation of the intertarsal joint presented medial deplacement of the gastrocnemius tendon and, consequently, the metatarsus bended in a

'EQM System, Yolancen Ltd., 1 Buckingham Street, York, YOIDW, England. 4 Model Number 1140, Instron S.A., 78530 Buc, France. ^ o d e l Number 1105, Instron S.A., 78530 Buc, France.

Percentage

65.50 Corn 19.00 Soybean meal (50% CP) 1.00 Animal fat 2.35 Maize gluten (60% CP) .30 Salt 3.05 Dicalcium phosphate 7.25 Limestone .60 Premix .05 DL-methionine .90 Ground straw Calculated analyses 2,810 ME, kcal/kg 16.50 Crude protein, N x 6.25% Lysine, % .73 Methionine, % .31 3.51 Calcium, % .60 Available phosphorus, % ^Providing the following vitamins and trace minerals per kilogram of diet: vitamin A, 10,000 IU; vitamin D, 1,500 IU; vitamin E, 15 mg; butylated hydroxy toluene, 125 mg; menadione, 5 mg; thiamine, .5 mg; riboflavin, 4 mg; calcium panthothenate, 8 mg; niacin, 25 mg; pyridoxine, 1 mg; vitamin B12, .008 mg; folic acid, 1 mg; biotin, 2 mg; cholin chloride, 500 mg; cobalt carbonate, .17 ng; copper sulphate, 4.4 mg; potassium iodide, .61 mg; sodium selenite, .11 (ig; zinc oxide, 42 mg; iron sulfate, 22 mg; and manganese oxide, 53 mg.

medial direction. Valgus angulation of the hock joint corresponded to angle between tibiotarsus and tarsometatarsus larger than 25° in the lateral direction. For tibial dyschondroplasia, a longitudinal cut was made across the proximal metaphysis of the right tibia in male and female chicks. Dyschondroplasia was considered to be present when an uncalcified plug of avascular cartilage was larger than 5 mm. Ash and biomechanical properties of the right tibia was evaluated at 1 day of age from 15 chicks (7 males and 8 females) and, thereafter, at 40 days of age from 40 birds (20 males and 20 females) hatched from the extreme weight subgroups fed on liberal or severe feed restriction. The biomechanical properties of the tibia were determined from a three-point stress test5 with rate of travel of the mobil anvil of .5 and .2 cm/min, and a bearer's width of 2.5 and 7.5 cm at 1 day and at 40 days of age, respectively. Ultimate and yield (corresponding to elastic deformation) force (in Newtons), stiffness (slope, Newtons

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(wk) 21 22 23 24 25 26 27 28 29 30 33 34 42 43 44 45 to 61

Liberal diet

BREEDER TREATMENTS AND PROGENY PERFORMANCE

247

^ilkinson, Leland Systat Inc., Evanston, IL 60201.

allowance has been previously demonstrated by other workers (McDaniel et al., 1981; Pearson and Herron, 1981; Ingram

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served. Similar BW were observed at 50 wk of age for ultralight and heavy hens when fed on liberal and severe restriction, respectively (difference in feed intake of 20 g / d a y per hen). Moreover, higher increases in BW were observed with age in the ultralight and light groups, irrespective of the feed allotment, as compared with the other groups (P<.05). The individual rate of egg production was unaffected by BW (Table 4), which is in agreement with observations on Leghorn hens (Harms et al., 1982). However, sexual maturity was delayed (P<.001) in proportion to the decrease in initial BW Statistical Analysis and the increase in feed restriction that The experimental design was a 4 x 3 was introduced 3 wk earlier. It is likely factorial arrangement of the treatments that the lighter hens at 21 wk of age ate with four weight groups and three feed less than the heavier ones during the intake groups. Each treatment group was rearing period as a consequence of comperepresented by 32 birds. The main effects tition for feed. This confirms previous were hen weights and feed levels. Two-way results showing that delayed sexual mainteractions were tested. Variations be- turity is elicited by feed restriction during tween individuals were used as error. Data rearing (Wilson et ah, 1983; Robbins et al., were subjected to the analysis of variance 1986). Moreover, severe feed restriction during the laying period significantly and the Tukey's test was used to separate impaired hen-day egg production (P<.001, differences between means. The calculaTable 4, Figure 1) in all hen size subtions were performed using the SYSTAT® groups. Numerous reports demonstrate 6 software program. Chi-square tests were that overrestriction depresses egg producused to compare the incidence of leg tion in both normal (Pym and Dillon, 1974; deformities. Proudfoot, 1979; Robbins et al, 1986) and dwarf broiler b r e e d e r s (Larbier, 1985; Triyuwanta and Nys, 1990a). In the presRESULTS AND DISCUSSION ent experiment, this depressing effect was Large standard deviations of BW due mainly to lowered performances at (coefficient of variation: 10%) were ob- peak of egg production which occurred at served in the flock at 21 wk of age despite around 30 wk of age (Figure 1). In the use of a similar feeding schedule for contrast, a moderate decrease in feed all hens during the rearing period. The intake maintained normal levels of egg average BW in the different groups at 21 production, as previously reported by wk of age ranged from 1.55 to 1.98 kg Leclercq (1986). (P<.001; Table 3). These differences in BW Fertility (P<.01) and, at a lower magniwere maintained throughout the laying tude, hatchability of fertile eggs (P<.05) period 0?<.001) as observed for laying were depressed when hens were fed a hens (Bish et al., 1985; Leeson and Sumliberal feed restriction schedule (Table 4). mers, 1987), but tended to decrease with An interaction between hen weights and age. Feed allowance had little effect on feed restriction regimens was significant BW at different ages of the hens, whatever (P<.05) at 58 wk of age and was d u e to an the initial BW of each subgroup. However, absence of depressive effect of liberal feed an interaction between BW groups and restriction on fertility in the ultralight feed consumption levels (P<.05) was ob- hens. This depressive effect of large feed per centimeter), and maximum deformation (bone deformation at the level of ultimate force, in millimeters) were measured on graphical records. The bones were then boiled for 1 h and etherextracted for 24 h. After drying at 110 C for 14 h, a mineralization test was carried out at 550 C for one night (18 h). The percentage ash was calculated as the ratio of ash to fat-free dry weight. Abdominal fat pads were weighed in 40-day-old chicks as described by Ricard and Rouvier (1967).

248

TRIYUWANTA ET AL. TABLE 3. Body weights of dwarf broiler breeders fed varied levels of feed from 21 to SO wk of age

Hen weight group 1

Feed restriction2

Age (wk) 21

30

1.983 1.91 1.96 1.95 ± 1.83 1.80 1.80 1.80 ± 1.74 1.72 1.67 1.69 ± 1.60 1.57 1.55 1.57 ±

2.55 2.47 Z59 252 ± .2 W 2.39 2.46 2.45 2.43 ± . l w Z32 2.33 2.24 2.30 ± . l x 2.22 2.14 2.30 2.22 ±.27

50

x ± SEM (21 to 50 wk)

flrr>

Heavy

.lw

.l x

.iy

.i z

2.79 2.74, 2.65 2.73 ± .2W 2.71 2.67 2.67 2.69 ± 2m 2.62 2.58 2.47 256 ± .3*y 2.62 2.45 2.48 252 ± 2V - Probability

2.47 ± 2* 2.37 ± . l a b 2.46 ± .l a 2.43 ± . l w Z33 ± 5 a b c 2.35 ± . l a b 2.37 ± . l a b 2.33 ± .l x 221 ± .l" 1 2.23 ± .l1**1 2.17 ± .l0*1 220 ± 2y 2.14 ± 2d 2.07 ± . l d 2.15 ± .2 d 2.11 ± 2Z

** NS NS NS * ** Means calculated for each weight and each feed intake group. Means with no common superscripts are significantly different (P<.05). w-2 In each column, weight groups means with no common superscripts are significantly different (P<.05). a Body weight at 21 wk: heavy, 1.95 ± .1 kg; medium, 1.80 ± .1 kg; light, 1.69 ± .1 kg; and ultralight, 157 ± .1 kg2 See Table 1. 3 n = 10 hens. *P<.05. W P<.01. NS NS

and Wilson, 1987). It supports the use of restricted feeding schedules during the laying phase. The mortality rate was low irrespective of the treatments and was not affected by feed restriction as observed by other workers (Pym and Dillon, 1974; Leclercq, 1986). Egg weights (evaluated at 43 and 57 w k of age; Table 5) increased in proportion to the feed allowance (P<.001), as previously reported by Pearson and Herron (1982) and Wilson et ah (1983) in normal broiler breeders and by Triyuwanta and Nys (1990b) in dwarf hens. Egg weights were also as a function of BW (P<.001), irrespective of the feed allotment, although the interaction between hen weight and feed restriction treatments was significant

(P<.05). In severely restricted hens, the differences associated with BW were lower than in liberally fed hens. This relationship between egg weight and body size has been demonstrated in layers (Bish et ah, 1985; Leeson and Summers, 1987) but was associated with parallel changes in feed intake in unrestricted hens. In broiler breeders, Lilburn and Myers-Miller (1990) observed no effect of initial BW, feed intake, or both on egg weights at 24 to 32 w k of age. Haugh units were generally lower in eggs from hens fed the intermediate feed restriction (P<.01) but were not influenced by BW. Shell quality was slightly affected by feed intake (P<.05). The highest feed intake was associated with a decrease in shell index in

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Liberal Intermediate Severe x ±SEM Medium Liberal Intermediate Severe x ±SEM Liberal Light Intermediate Severe x ±SEM Liberal Ultralight Intermediate Severe x ±SEM Source of variation Hen weight (HW) Feed level (FL) HW x FL interaction

249

BREEDER TREATMENTS AND PROGENY PERFORMANCE TABLE 4. The effect of hen body weight and feed level restriction on sexual maturity, egg production, fertility, hatchability, and mortality rate of dwarf broiler breeders

Feed restriction2

Heavy

Liberal Intermediate Severe Liberal Intermediate Severe Liberal Intermediate Severe Liberal Intermediate Severe

Medium Light Ultralight

Sexual maturity (days) 172.4b 174.0b 175.5b 175.6b 176.3ab 177.8ab 176.2ab 177.3ab 178.0ab 177.2ab 177.6ab 181.7*

Mortality rate (24 to

58.6s4 58.3a

3 2 3 5 1 1 3 5 2 2 3 5 1.3

SOT1" 60.4 a 60.4 a 48.2 b 59.5 a 58.7° 52.6 b 60.1 a 58.9* 53.3 b

61 wk)

Fertility (44 and 58 wk) (%) 81.5ab 88.4ab 89.9ab 82.2ab 91.2a 92.6a 81.1ab 877ab

89.4ab 85.7ab 77.4b 852 ab 14.4

Hatchability (44 and 58 wk) 78.3b 87.3ab 82.5ab 83.7ab 81.8ab 88.2ab 76.0b 80.1ab 86.2ab 82.1ab 81.6ab 89.7* 17.2

SEM 7.2 115 Source of variation ** NS NS NS Hen weight (HW) NS *+ * ** NS ** Feed level (FL) NS NS NS NS HW x FL interaction a,b Means within each column with no common superscripts are significantly different (P<.05). 1 Body weight at 21 wk; heavy, 1.95 ± .1 kg; medium, 1.80 ± .1 kg; light, 1.69 ± .1 kg; and ultralight, 1.57 ± .1

%

2

See Table 1. hatchability of fertile eggs. *n = 34 hens per treatment. *P<.05. **P<.01.

INTERMEDIATE

AGE (WEEKS)

FIGURE 1. Egg production of breeder hens fed varied levels of feed. Liberal (•), intermediate (•), and severe (o) feed restriction are described in Table 1.

part of the weighing groups but the interaction between hen weight and feed restriction treatments was highly significant (P<.01). The decrease in shell breaking strength observed in hens fed liberally supports the hypothesis of a depressive effect of high feed intake on shell quality. However in the present experiment, impaired shell quality was not followed by impaired hatchability, as previously reported by McDaniel et al. (1981). Day-old chicks were heavier when produced from the heavier hens (P<.01, Table 6) and from hens fed on liberal restriction (P<.01). The broiler males were heavier than the broiler females (P<.05), which is in agreement with other observations (Spratt and Leeson, 1987; Proudfoot and Hulan, 1987). There are few reports in the literature detailing the effects of

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Hen weight group1

Egg production (24 to 61 wk)

250

TRIYUWANTA ET AL. TABLE 5. The effect of hen body weight and quantitative feed restriction on egg quality in dwarf broiler bleeders

Hen weight group 2 Heavy Medium Light

Liberal Intermediate Severe Liberal Intermediate Severe Liberal Intermediate Severe Liberal Intermediate Severe

SEM Source of variation Hen weight (HW) Feed level (FL) HW x FL interaction

Egg weight (g) 66.9a 66.1* 645 b c d 66.1* 63.6de 65.9abc 64.2 bcd 62.3e 64.5 bcd 63.9cde 632de 4.9

*

Haugh units 91.3* 90.1* 91.9* 91.9* 90.0* 90.7* 90.5* 89.6b 92.1a 89.4b 89.6b 91.1* 72

Shell index

Shell breaking strength

(g/dm 2 ) 74.7° 78.8a 78.4*

(kg) 2.04 2.17 2.23 2.13 2.08 2.13 2.16 2.17 2.21 2.19 2.18 224 .54

7 7 ijabc

75.8abc 75.5C 74.9C 78.4* 78.7ab 78.4* 78.0abc 77 7abc 8.1

NS

NS

St*

* **

NS

NS NS NS

a-e

Means in the same columns with no common superscripts are significantly different (P<.05). 1 n = 74 to 82 eggs per treatment. 2 Body weight at 21 wk; heavy, 1.95 ± .1 kg; medium, 1.80 ± .1 kg; light, 1.69 ± .1 kg; and ultralight, 1.57 ± .1 kg-

3

See Table 1. »P<.05. **P<.01.

breeder diets or breeder body weights on subsequent body growth of their progeny. Energy restriction in breeders has been shown to diminish chick weight at hatching (Schumaier and McGinnis, 1969; Spratt and Leeson, 1987; Triyuwanta and Nys, 1990b) and this can result in decreased BW at market age (P<.01; Table 6; Triyuwanta and Nys, 1990a). However in numerous reports (Wilson and Harms, 1984; Spratt and Leeson, 1987; Proudfoot and Hulan, 1987) no consistent effect of parental feed restriction was observed on the BW of the progeny. On the contrary, there is convincing evidence that day-old chick weight is influenced by egg weight (Shanawany, 1987; Wilson and Harms, 1988) and that broilers hatched from large eggs are heavier at slaughter age (Tindell and Morris, 1964; Wyatt et al., 1985). However, initial differences in egg weights and in day-old broiler chick weights must be very large to have an

influence on subsequent BW weights at market age (Al-Murrani, 1978; Pearson and Herron, 1982; Spratt and Leeson, 1987). Such an influence of egg weight on chick weight has already been demonstrated for variations of egg weight with age of the breeder hens (McNaughton et al., 1978; Wilson and Harms, 1988; Sinclair et al., 1990). Similarly, the association of chick BW with the hens' weight grouping (Table 6) resulted partly from the increase in egg weight. It is also likely that variability in individual genetic potential of the hens was responsible firstly for heterogeneity of hen weight and secondly for part of the difference in progeny weight, as the strain factor influences growth rate of the offspring (Proudfoot et al., 1982). On the other hand, livability was not influenced by the treatments. The abdominal fat pad tended to be heavier in female broilers hatched from larger and liberally fed hens, and was higher in

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Ultralight

Feed restriction3

251

BREEDER TREATMENTS AND PROGENY PERFORMANCE

TABLE 6. The effect of hen body weight and feed level restriction on progeny performance of dwarf broiler breeders Body weight3,4 1 day 40 days F M F

Feed restriction2

M

Heavy

Liberal Intermediate Severe Liberal Intermediate Severe Liberal Intermediate Severe Liberal Intermediate Severe

(g) 45.4* 43.3*b 44.2abc 43.7* 44.3*bc 42.7*b 44 jab 43.5* 425 b c d 42.3*b 42.6bcd 42.0*b 44.8ab 43.1 ab 42.0od 41.6*b 421bcd 41.6ab bcd 43.4* 43.6 43.2bcd 42.6*b 41.6d 41.5b 3.4 354

Medium Light Ultralight

•

*g) 150* 1.45*b bcd 1.45*b 159 1.72* 1.37b 157°* 1.42*b 1.40b b 1.69* 1.43*b 150* 155 d 1.42*b d 1.44*b 156 1.65*°* 1.40b 155 d 1.44*b .14 .16 - Probability ** NS ** NS 44 **

Abdominal fat content3 M F (%) -

1

1.67»bc

Mortality rate

2.7

3.4*b b

2.9

2.9

2.9

3.6*

2.8 .7

3.2*b .6

3 2 3 5 1 1 3 5 2 2 3 5 1.3

SEM Source of variation ** * Hen weight (HW) NS NS NS ** ** Feed level (FL) NS NS ** *+ *• NS ** ** Sex Interactions NS NS •» NS NS HW x FL ** NS ** NS HW x sex NS ** * FL x sex NS ** NS HW x FL x sex a Means in the same columns with no common superscripts are significantly different (P<.05). 1 Body weight at 21 wk: heavy, 1.95 ± .1 kg; medium, 1.80 ± .1 kg; light, 1.69 ± .1 kg; and ultralight, 1.57 ± .1 kg2See Table 1. 'hA = male; F = female. *n = 50 to 60 chicks. 5 n = 20 chicks. »P<.05. *»P<.01.

females than in males (P<.01). In contrast, Spratt and Leeson (1987) had observed a decrease in fat content in male offspring hatched from breeders fed high feed levels. Both maternal BW and feed intake had a marked effect on tibial bone strength of the offspring at 1 day (Table 7) and at 40 days of age (Table 8). The ultimate force, elastic force, stiffness, and ash content of tibiae were higher (P<.01) in day-old chicks hatched from heavier hens and hens fed on liberal restriction. At 40 days of age, these parameters, as well as the tibial length, were affected by hen size (P<.01) but the effect of feed intake was

not significant (P>.05). Bone breaking strength and tibial ash content were higher in males than in females at 40 days of age (P<.01, Table 8). Tibial ash content was increased at hatching, in males when compared with females (P<.05, Table 7). The tibia was also longer in males than in females (P<.01) at slaughter age (Table 8). The cortical thickness was highest in male broilers hatched from heavy breeder hens as compared with ultralight hens. No interactions were observed at either age except for a feed level by sex effect (P<.05) and a hen weight by feed level by sex (P<.01) effect occurring at 40 days for stiffness.

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Hen weight group 1

252

TRIYUWANTA ET AL. TABLE 7. The effects of hen body weight and feed level restriction on subsequent ossification of broilers at hatching

Variable

Yield force

Ash content

6.41 5.3** .9

4.6 3.9** .9

Maximum deformation (mm) 1.33 1.31 .05

6.31 5.5" 1.0

45 4.0* .9

1.40 1.23* .05

76.7 66.2** 15.1

30.7 29.8 3.8

5.92 5.8 1.1

4.3 4.2 1.0

1.33 1.31 .20

70.5 72.6 16.0

31.3 29.0* 4.0

ON)

i

Stiffness (N/cm) 79.5 63.4** 13.8

31.7 28.8** 3.5

(%)

n = 30 chicks per treatment. ^T\ = 28 males and 32 females per treatment. *P<.05. **P<.01.

These changes in bone morphology and gastrocnemius tendon was observed in 35% mineral contents affected the incidence of of the birds affected by valgus deformaleg abnormalities only slightly. The tion. However, an increased occurrence of amount of varus and valgus deformations tibial dyschondroplasia was observed in was similar regardless of the hen size and broiler hatched from heavier breeder hens feed intake (Table 9). Varus angulation (P<.05) with no influence of hen feed affected the right limb in 80% of the cases intake. The results on bone composition but valgus limb deformation was a bilat- confirm a previous observation on the eral abnormality. Lateral slipping of the effect of breeder feed intake on bone

TABLE 8. The effect of body -weight and feed level restriction of dwarf broiler breeders on bone mineralization of the progeny at 40 days of age Variable Hen weight Heavy Ultralight SEM Hen feed restriction Liberal Severe SEM Sex Male Female SEM 1

Tibia length (cm)

Ash Cortical Maximum Elastic Maximum thickness force force deformation Stiffness content (mm) •(N) - (mm) (N/cm) (%)

9.51 9.3** .3

2.9 2.6** .6

265.9 233.0** 65

171.1 154.9* 48

3.4 3.2 .6

1,217 1,113* 278

48.2 44.9** 4

9.41 9.4 .3

2.7 2.8 .6

255.7 242.4 67

170.6 154.8* 48

3.2 3.3 .6

1,209 1,117* 277

46.3 46.8 5

9.71 9.3** .3

2.8 2.6* .6

267.2 232.8** 66

173.4 152.4** 49

3.4 3.1* .6

1,258 1,074** 267

47.1 45.8* 4.2

n = 80 birds per treatment. *P<05. **P<.01.

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Hen weight Heavy Ultralight SEM Hen feed level Liberal Severe SEM Sex Male Female SEM

Ultimate force

BREEDER TREATMENTS AND PROGENY PERFORMANCE TABLE 9. The effect of body weight and feed level restriction of dwarf broiler breeders on the incidence of leg abnormalities of the progeny at 40 days of age Variable

Dys.W

Varus Valgus

specific element. Furthermore, the magnitude of the positive effect of feed allowance and maternal BW on bone quality was far larger than the increase in egg weight. These observations suggest that the genetic background of the female is important in explaining the improvement of bone quality. In conclusion, the present experiment demonstrates that the performance of dwarf female breeders depends mainly on the level of feed restriction but that progeny performance and, especially, bone strength of progeny, depend on body size and feed intake of the female breeders. The origin of this effect is unknown. It is also uncertain whether the depressive effect of breeder feed restriction on bone characteristics of their progeny can be corrected by an additional mineral or vitamin supplementation in the broiler diet. ACKNOWLEDGMENTS The authors are grateful to P. Constantin for evaluation of valgus and varus incidence on the broiler chicks. J. M. Meslier, J. Courtemanche, and E. Desnoes are thanked for assistance in rearing the birds.

quality (Triyuwanta and Nys, 1990a), where similar positive effect of feed allowance or phosphorus intake on tibial ossification was observed at hatching. These authors also noticed the effects tend to diminish with age of the progeny whatREFERENCES ever the nutritional origin. The effects of breeder feed intake and parent size were Al-Murrani, W. K., 1978. Maternal effects on embryonic and post-embryonic growth in poultry. Br. additive with a predominance for the Poult. Sri. 19277-281. latter character. Both effects were more Beer, A. E., 1969. A review of the effects of nutritional deficiencies on hatchability. Pages 93-108 in: marked at hatching versus older ages. It is The Fertility and Hatchability of the Hen's Egg. likely that maternal effects on BW influT. C. Carter and B. M. Freeman, ed. Oliver and ence the rate of embryonic development. Boyd, Edinburgh, Scotland. It has already been demonstrated that Bish, C. L., W. L. Beane, P. L. Ruszler, and J. A. Cherry, 1985. Body weight influence on egg maternal nutritional deficiencies impair production. Poultry Sci. 64:2259-2262. hatchability of eggs, elicit abnormalities of R., M. M. MacCowan, and W. Bolton, 1976. the skeleton (Beer, 1969), and could also Blair,Effects of food regulation during the growing increase the incidence of leg problems in and laying stages on the productivity of broiler breeders. Br. Poult. Sci. 17:215-223. growing broilers (Whitehead, 1989). Moreover, feeding breeders with diets deficient Blum, J. C, J. Simon, and M. Larbier, 1979. Importance du milieu et des conditions nutriin vitamins, trace elements, or amino acids tionnelles pendant les premiers stades de la vie reduces postnatal growth (Blum et al., sur les developpements statural et fonctionnel des oiseaux. Ann. Biol. Anim. Biochim. Biophys. 1979). The present experiment was carried 19:303-319. out to study the effects of an overall Harms, R. H., P. T. Costa, and R. D. Miles, 1982. parental feed restriction on the progeny, Daily feed intake and performance of laying thus diminishing the overall supplies in hens grouped according to their body weight. Poultry Sci. 61:1021-1024. nutrients. A consequence of this was that the deleterious effects on bone growth of Ingram, D. R., and H. R. Wilson, 1987. Ad libitum feeding of broiler breeders prior to peak egg the progeny could not be attributed to a production. Nut. Rep. Int. 36:839-843.

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- (%) Hen weight 11.8 •65 3.1 Heavy 32 4.8 Medium 5.5 4.8 Light 2.6* 2.4 7.3 Ultralight Hen feed restriction 6.4 3T 6 8.1 Liberal .9 1.7 Control 7.9 4.3 4.9 Severe Male and female. ^ = 76 to 78 chicks. Dys. = dyschondroplasia. 4 Male. 5 n = 145 to 188 chicks. 6 n = 184 to 246 chicks. •Significantly different from the heavy group (P<.05).

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