Health and growth in young goats fed pelleted lucerne or concentrate ad libitum

Small Ruminant Research ELSEVIER

Small Ruminant Research 13 (1994) 109-115

Health and growth in young goats fed pelleted lucerne or concentrate ad libitum S.M. Thamsborg *'a, R.J. JCrgensen a, J. Fogh b, M.N. Mgasa c ~Department of Clinical Studies, Large Animal Medicine and bDepartment of Animal Health and Production, Royal Veterina~ and Agricultural Universi~, Biilowsvej 13, DK 1870 Frederiksberg C, Denmark ~Facul~ of Veterinary Medicine, Sokoine Universit 3, of Agricuhure, P.O. Box 3020, Morogoro, Tanzania (Accepted 25 June 1993)

Abstract Twenty male kids of the Danish Landrace, in two groups of ten each, were fed ad libitum whole barley and pelleted protein supplement (group A) or forage pellets (mostly lucerne) (group B), from 1 mo of age until slaugther 3 mo later. Both groups had free access to hay. Apart from subclinical acidosis initially, group A remained healthy, showed acceptable weight gain ( 197 g/day) and produced marketable carcasses. In contrast, group B had clinical coccidiosis, signs of undernutrition, lower blood Mg, inorganic P, glucose, Se, and produced a significantly lower mean weight gain ( 111 g/day, P < 0.001 ). Carcasses of group B had poor muscular conformation and were found unsuitable for the Danish market. Reasons why coccidiosis reached clinical levels in group B but not in group A, were probably nutritional stress and a wet environment favouring oocyst development and survival. Although the price per kg weight gain was 21% lower in group B compared to group A, it was concluded that lucerne pellets offered ad libitum, directly off nursing milk, without mineral or energy supplementation, can not be recommended for finishing young male kids for market kid production. Key words: Goat; Feeding, ad libitum; Lucerne pellet; Hypophosphataemia; Coccidiosis

1. Introduction As a result of relatively high fertility in goats, with kidding rates often well above 2, goat milk producing farms in Denmark generally have a large surplus of kids. Numbers of female kids exceed the demand for replacement animals and, in particular, male kids are often killed at birth because of marginal profit, if any, in rearing them for meat production. In the present experiment, health and growth in rearing male kids *Corresponding author. 0921-4488/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved S S D 1 0 9 2 1 - 4 4 8 8 ( 9 3 ) E007 l - Y

under Danish conditions was examined for the first time comparing diets of two different levels of energy, namely a concentrate based on barley and a pelleted dried green forage, mostly lucerne. Automatic ad libitum feeding was choosen in order to minimize the cost of labour as well as health hazards such as bloat, diarrhoea and ruminal acidosis known to be related to restricted feeding of milk-fed and juvenile ruminants. Lucerne pellets contained less energy per unit DM than concentrates. However, lucerne pellets were chosen due to the relatively lower market price, less risk of over-eating and that favourable feed con-

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version was obtained when given as the sole feed, besides straw, to fattening bull calves (JCrgensen et al., 1993) and sheep (Jcrgensen and Thamsborg, 1989, personal communication). Goats are, however, known to be a more selective feeder (Kay, 1989) and it was therefore an open question whether voluntary uptake of unsupplemented pellets would be tolerated without producing ill-health and whether it would meet requirements for energy, protein and minerals in growing kids. Part of the study concerned with forestomach and digital development and pathology was reported by Mgasa et al. (1994).

2. M a t e r i a l a n d m e t h o d s

2.1. Experimental animals" Two- to 4-wk-old, male kids of the Danish Landrace were obtained from a dairy goat farm. All kids had received colostrum for the first 3 days of life and thereafter a high quality milk replacer based on skim milk powder ( KIP, Leo Pharmaceutical Industries Ltd., DK 2750 Ballemp).

2.2. Experimental design, feeding and housing Kids were offered an acidified whey-based milk replacer (Spray Top, Ewos-Kemovit A / S , DK 7000 Fredericia) from arrival. The first week (wk - l ) increasing amounts were given twice daily at room temperature from a lamb bar (Table l ). The start of the ad libitum milk feeding the following week was defined as the start of wk 1. At the same time, kids were randomly allocated to two experimental groups of ten, and the experimental feed was introduced. Group A was offered pelleted protein concentrate plus whole barley in a mixture of 1:3. The protein concentrate had macro- and microminerals plus vitamins added. Group B was offered pelleted artificially dried green forage, minimum 90% w / w lucerne (Medicago sativa), containing no additives (Table 2). The in vitro organic matter digestibility coefficient of the lucerne pellets was 0.59 (Tilley and Terry, 1963). DE was calculated according to M¢ller et al. (1983) and was multiplied by 0.82 to obtain ME. Both groups had access to water and medium quality meadow hay (grass) ad libitum. Groups were confined indoors on concrete at 20°C in cubicles separated by iron bars. Barley straw was the bedding, changed daily in order to keep cubicles clean and dry. At weekly intervals, the feed in the self-feeders was weighed and

Table I Design including feeding in relation to experimental week and BW at entry of periods. Hay offered ad libitum Week No.

- 1

Length of period

Average age in weeks

Feeding

group A

group B

3

5.7±1.0

5.4±1.0

4

6.9+1.0

6.7±1.1

I week

I +2+3

3 weeks

4 to 13

10 weeks

Arrival Increasing amounts of milk replacer fed twice daily and hay ad lib. Milk replacer ad lib. Group A: concentrate and hay ad lib. Group B: lucerne pellets and hay ad lib.

7

17 ~Mean__+SD.

Bodyweight (kg) ~

9.1±1.2

8.7±1.3 Group A: concentrate and hay ad lib. Group B: lucerne pellets and hay ad lib. Slaughter

S.M. Thamsborget al./ Small RuminantResearch 13 (1994) 109-115 Table 2 Feed composition (% of DM) in the two types offered ad libitum Analyses

DM ( % ) CP Ca P Mg Se (ppm)

ME (MJ/kg DM) g DP/kg feed g DP/kg DM

Concentrate ( group A)

87.0 14.0 0.58 0.53 0.17 0.33 12.4 115.0 132.2

Lucerne pellets (group B ) 91.0 16.1 0.99 0.26 0.17 0.12 9.3 93.5 102.7

replaced with new feed. All kids were weighed at the same time.

2.3. Observations and sampling Daily recordings were made on general appearance, digestive disorders, lameness and any other signs of ill health. Rectal faecal samples were examined for helminth eggs and oocysts o f coccidia by means of a modified McMaster technique using a 50% w / v glucose in saturated NaC1 solution for flotation (Henriksen and ,~g~rd, 1976). Samples were obtained from all animals at wk 10, 12 and twice in wk 13. In the early part of the study, intestinal contents were also examined for cryptosporidia according to Henriksen and Pohlenz (1981). Blood was sampled in vacutainer tubes by jugular venipuncture from all animals wk 10 and 12. EDTAsamples were analysed for haematocrit using a microhaematocrit centrifuge. Heparinized plasma samples were analysed for Ca and Mg by atomic absorption spectrometry, non-esterified (inorganic) P, glucose and lactate using standard commercial kits (Roche Ltd. and Boehringer Mannheim Ltd.). Serum was analysed for total protein with a commercial kit (Roche Ltd. ) and for albumin by the bromcresolgreen method (Nisbeth et al., 1973). In wk 12, heparin full-blood from all animals was further analysed for Se ( Hasunuma et al., 1982). One animal from each group was euthanized and their gastrointestinal tract, including forestomach development, was examined at the end of wk 4, 6 and 9 ( M g a s a et al., 1994). At termination of the experiment ( w k 13 ), all remain-

111

ing animals were slaughtered and the carcasses were assessed for marketing by two experienced butchers. None were informed of the design of the experiment or feeding of animals.

2.4. Statistical analyses The geometric means of coccidia counts were calculated: M ( g e o ) = exp[ 1 / n Z I n ( x + 10) ] - 10, where n is number of animals and x is number of coccidia oocysts per g ( O P G ) . Group means of blood parameters, weight gains and log-transformed coccidia oocyst counts were compared using a t-test ( P < 0.05) ( S A S , 1988). The 2 days of blood sampling in wk 10 and 12 were compared by paired t-test ( P < 0.05).

3. Results 3. I. Observations during the preliminary adaptation period One lethal case of a bloat-like syndrome was observed on the day of arrival and a further case 2 d later. Post mortem examination revealed yellow-white, sour smelling contents with gas formation in the reticulo-rumen, abomasum and small intestine, probably caused by rapid fermentation of the milk ration. No further cases were observed after the self-feeder system was applied. Diarrhoea was observed in some animals upon arrival. The farm had a history of cryptosporidiosis cases (Thamsborg et al., 1990) and faeces from three randomly selected animals were submitted for examination of cryptosporidia infection. Of these, one was positive. Table 3 Excretion of coccidia oocysts in faeces

Group A Group B

Week l0

Week 12 (n=7)

Week 13 start (n=7)

Week 13 end (n=5)

(n=8) 21 300~ 305 000b

10500 a 37 300a

15800~ 12 700a

14600a 35 200a

All data are geometric means of oocyst counts (oocysts per g faeces (OPG) ) ; n = number of animals; "'bdifferentsuperscript indicate significantdifference (t-test: P < 0.05 ).

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Table 4 Selected blood parameters Parameter

Week No.

Group A ( n = 8/7 )

Group B (n = 7/6)

Ref.~

Mg ( mmol/I )

10 12 10 12 10 12 12

1.16 +0.09 1.10_+0.06 3.14_+0.54 3.41 +0.51 4.45___0.35 4.21 ___0.27 0.23 _+0.02

0.95 +0.09*** 0.98_+0.06** 1.62_+0.32"** 2.09+0.45*** 3.36_+0.55*** 3.23-+0.13"** 0.08 _-t-0.02"**

0.85-1.10

P (mmol/l) Glucose (mmol/I) Se ( mg/I )

1.91-3.94 3.5-5.2

All data are means + SD; n = number of animals wk 10/wk 12. **Denotes significant difference P < 0.01 : ***P < 0.001. "5th to 95th percentiles (Mbassa, 1991 ).

16]

Table 5 Daily feed intake, performance and daily ration during the ad libitum period (week 4-12)

kg

1, 1 12 ]

;

lO i

i

~I 6~

Group A

Group B

471 3.04 69 31.85 197+10" 0.18 0.96

501 3.90 74 45.72 Ill 24a 0.08 0.76

Requirements

***

***

T

11

12

TY

i

4~

DMI/d/animal (g) DMI ( % of BW) DM1/BW~)75 (g) ME/BWG/d (MJ/kg) BWG(g/d) (n=7) Price, daily ration (US$) Price/kg BW gain (US$)

2

0

1

2

3

4

5

6

7

8

9

10

week

Fig. 1. Mean liveweight gain in seven goats in each group ( group A, crosses; group B, diamonds). *P < 0.05; **P < 0.01 ; ***P < 0.001.

Ration per day: ME, MJ DP (g) Ca (g) P (g) Mg (g)

5.9 62 2.7 2.5 0.8

4.6 50 5.0 1.3 0.9

6.9-7.8 b 45-51 b 3b 2.1 b 1.0~

"Mean+SD., n=number of animals, significantly different, P<0.001. Requirements according to bNRC ( 1981 ) for 6-18-week-old kids, weighing 10-15 kg, maintenance plus growth of approx. 150 g/day and ~Haenlein (1990) (0.2% of ration).

g/kg M B W T / d a y 100

80

60

3.2. Observations during the experimental period A t the e n d o f w k 6, goat No. 18 in g r o u p B l o o k e d d e p r e s s e d , had c o l d l i m b s and pale m u c o u s m e m b r a n e s but w a s not d e h y d r a t e d . F a e c e s a p p e a r e d n o r m a l and

20

o

1

2

3

4

5

6

7

8

9

10

11

12

week

Fig. 2. Mean daily DM intake of experimental diets per kg metabolic BW of goats (group A, filled; group B, hatched).

coccidial o o c y s t c o u n t was 174000 O P G . Several goats in g r o u p B d e v e l o p e d d i a r r h o e a in w k 10 and o n e goat ( N o . 14) died. B l o o d s a m p l e s o f this a n i m a l taken 2 d earlier s h o w e d very l o w b l o o d Ca, P and g l u c o s e , w h i l e lactate ( 2 . 4 6 m m o l / l ) w a s elevated, indicative o f a s y s t e m i c acidosis. A n o t h e r goat ( N o . 2) in g r o u p B

S.M. Thamsborg et al. / Small Ruminant Research 13 (1994) 109-115

was very weak and had severe anaemia, hypoalbuminaemia, very low blood P and Mg, and lactic acidosis (3.75 mmol/1). Faecal samples for coccidia oocysts at the same time showed that group B had a higher level of oocyst excretion than group A (P < 0.05, Table 3). In group B, the two goats mentioned (Nos. 14 and 2) had the highest counts, 1.5 X 106 and 1.0x l06 OPG, respectively. After 1 week, the clinical symptoms of diarrhoea subsided, and goat No. 2 had fully recovered after 2 wk. Diarrhoea was not observed in group A. In general, goats of group A appeared healthy and active and strongly resisted blood sampling throughout the experiment. Group B had a more docile behaviour, appeared weak when handled and had poor body and muscular condition. It was noted that throughout the study the straw bedding in group B was generally more wet when removed daily from the cubicles. Significant lower group means of plasma Mg, inorganic P, glucose and Se were found in group B (Table 4). Other blood constituents showed no significant differences between groups. In wk 10, the level of P in group B was almost half the level of group A, and considerably lower than values obtained from 64 healthy dairy goats of same age and analysed by the same laboratory ( Mbassa, 1991, pp. 65-78). Sherman and Robinson (1983) list 2.7-3.3 mmol P/1 as normal values for juvenile goats. Both groups had comparable level of blood Ca and were considered normocalcaemic. Comparing the two times of blood sampling, the only significant change was a decrease in plasma glucose of group B from wk 10 to 12 ( P < 0 . 0 5 )

3.3. Weight gain, feed consumption and carcass quality Weight gain during the preliminary period (wk 13) was comparable but thereafter group A had a substantially and consistently higher daily weight gain (Fig. 1). Intake of hay was not assessed, nor any intake of straw bedding. During the first 2 wk, DM intake (DMI) of experimental feeds was minimal. In wk 3, when milk replacer was gradually reduced, increasing amounts of feed were eaten and up to wk 10 the DMI per goat was increasing but still comparable in the two groups. When DMI was corrected for BW °~75, it was increasing in the beginning of the study but levelled out, and in all weeks it was higher in group B than A (Fig. 2). Daily weight gain was 77% higher in group A compared to B ( P < 0 . 0 0 1 ) and the ratio of ME to weight gain was lower in group A than B (Table 5).

113

Daily intake of energy from experimental diets per kid was 27% higher in group A compared to B and in both groups, the intake was less than required according to NRC (1981) (Table 5). The difference in intake of ME was even more pronounced in the latter part of the study (40% in wk 9-12). The price per kg weight gain was 21% less in group B compared to A. At slaughter, five animals of group A were assessed as good quality and suitable for marketing. In contrast, five carcasses of group B had poor muscular development and none of them were regarded as marketable in Denmark. The remaining four carcasses were not subjected to evaluation.

4. Discussion A marked difference in health and production of young goats was found between the two diets. Group A fed concentrates had very good growth rate, no clinical problems and produced a marketable product. Concentrate offered ad libitum produced no clinical signs of overeating or laminitis. In contrast, group B fed pelleted green forage, mostly lucerne, had poor performance and no marketable carcasses. Group B was in a marginal state of P deficiency judged from low blood P, which was likely due to low P content in the diet and perhaps the high level of Ca limiting intake ( Blood and Radostits, 1989, pp. 1205-1209). The ratio of Ca/P was 3.8:1, which differs markedly from the ratio of 1.2:1 traditionally recommended (Haenlein, 1987). However, the clinical or productional implications of a ratio higher than recommended is questionable, and Gueguen et al. (1988) mention that even a high Ca/P ratio (8:1 ) does not significantly affect absorption of P. Low P intake is known to produce deficient mineralisation of bones, classical signs of rickets and osteomalacia often seen in cattle being most susceptible, and in growing sheep (and probably goats) manifested as unthriftiness and poor body conformation (Blood and Radostits, 1989). We found no signs of rickets but poor development of bones and thin compacta that could be described as an osteodystrophy probably associated with osteoporosis (Mgasa et al., 1994). Different levels of protein in the diets could have contributed to differences in the formation of bone matrix. According to Puls (1988, pp. 198-200), Se blood

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S.M. Thamsborg et al. / Small Ruminant Research 13 (1994) 109-115

level of 0.04-0.08 mg/l is considered marginal in sheep, whereas Sherman and Robinson (1983) list normal values for goat and sheep as 0.05-0.4 mg/1. It was concluded that group B was very low in Se and probably in a state of marginal deficiency. However, no clinical signs of nutritional muscular dystrophy were seen. Low Se is known to occur in areas of Denmark when ruminants are fed a home-grown diet without supplementation (Jensen and Agerg~rd, 1981). The role of Se in ill-thrift seems still unclear (Blood and Radostits, 1989). Kids received in the experimental diets alone the ME required for maintenance (NRC, 1981; Trodahl et al., 1981). The 7% higher intake of pellets (DM/kg BW °'75) indicates that group B had to compensate for the lower level of ME in this feed by increasing DMI. This was reflected in heavier filled forestomach/kg BW at slaughter ( Mgasa et al., 1994). It is likely that rumen capacity was a factor restricting intake of pellets (Forbes, 1986) wk 10 onwards (Fig. 2). Intake of hay was not known. However, it is probable that group A had considerable intake of hay considering the listed requirements of ME for a growth rate of 200 g/day is approx. 50% higher than was the ME in the actual intake of concentrates (NRC, 1981 ). Group B probably had less capacity for intake of hay. This is also reflected in the large difference between A and B of ME in experimental diets in relation to weight gain (Table 5). It is well known that a few or a single species of coccidia are more pathogenic than others (Schillhorn van Veen, 1986). As a consequence, Yvore and Esnault (1987) recommend coccidial oocyst counts with differentiation of pathogenic species whereas others consider undifferentiated oocyst counts a good diagnostic aid (De la Fuente and Alunda, 1992). Combining the clinical observations and faecal examinations in this study, it seems evident that the kids fed lucerne pellets suffered from coccidiosis after 10 wks. Coccidial infections did not reach clinical levels in group A fed concentrates. Unfortunately, oocyst counts were not performed prior to the unexpected out-break of coccidiosis. Considering that the feed factor was the only variable between the groups, that all kids were from the same farm, were purchased as one group and kept as such until wk 1 of the experiment, we suggest that the outbreak was linked with the feed. However, influence of diet on coccidial infections is only poorly described in

the literature. Contaminated environment and stressrelated reduced immunity are regarded to be of major importance in development of coccidiosis (Schillhorn van Veen, 1986). A poorer feed related immune response in group B could partly explain our results; but also an indirect effect of feed on gut environment, favouring coccidial propagation, and the more wet environment in the pen, probably caused by higher water consumption, may have played a role. The outbreak was folllowed by a sharp fall in oocyst output (Gregory et al., 1981, 1982) Reduced growth rate for longer periods is a common finding in clinical and subclinical coccidiosis (Foreyt et al., 1986) and is probably due to profound changes in the gut mucosa. However, to what extent coccidiosis and diet, respectively, or interactions, affected the growth rate cannot be determined in the present study. Coccidiosis may also have affected uptake of P in the small intestine thereby exacerbating effects of low P in the diet. Aumont and coworkers (1986) found no changes in Ca or P balance in experimental infections in goats but it has been shown in sheep that chronic trichostrongylosis, also affecting the small intestine, results in a marked hypophosphataemia and ill-thrift (Sykes et al., 1975; Coop and et al., 1976). Alterations of blood parameters including decrease in P and Ca have earlier been reported in coccidia infected kids ( S hommein and Osman, 1980). Further investigations on interactions between diet and coccidial infections are warranted.

5. Conclusion

Ad libitum feeding of a mixture of barley and pelleted protein concentrate plus hay resulted in good health, acceptable feed conversion, growth rate and carcass quality. Feeding lucerne pellets and hay resulted in much slower growth rate and mineral deficiencies. As a consequence, the latter group was not fit for slaughter at the time the concentrate group was slaughtered. Although the daily cost of feeding lucerne pellets was lower, such feeding without mineral and energy supplementation appears not to be advisable for growing and finishing healthy kids.

S.M. Thamsborg et al. / Small Ruminant Research 13 (1994) 109-115

Acknowledgements We are grateful to Dr. S.A. Henriksen, National Veterinary Laboratory for cryptosporidia examinations, to the staff at The Central Laboratory, Dept. of Clinical Studies for blood analyses and to Mrs. Anette Pedersen for skilled technical assistance. This study was funded by Ewos-Kemovit A/S, DK-7000 Kolding, and the Danish Agricultural and Veterinary Research Council (Grant No. 13-4266).

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