Growth, carcass and meat quality in veal calves fed diets based on wholemilk or milk replacers.

Abstract

254 Proc. Aust. Soc. Anim. Prod. Vol. 17 GROWTH, CARCASS AND MEAT QUALITY IN VEAL CALVES FED DIETS BASED ON WHOLEMILK OR MILK REPLACERS J.B. MORAN*, G. GAUNT** and A. J. SINCLAIR*** SUMMARY Friesian bull milk-protein-based concentrate pellets 16 weeks of age and calves were fed 8 l/day of wholemilk, wholemilk plus soyflour, replacer or replacer plus soyflour together with ad lib from 8 to 16 weeks or age. Calves were slaughtered at 12 or carcass and meat quality was assessed. The inclusion of soyflour in the liquid diet reduced growth rates of calves, However, meat from calves fed soyflour contained a higher proportion of polyunsaturated fatty acids while the highest proportion of saturated fatty acids was found in meat from calves fed wholemilk. It was concluded that at a substitution rate of 0.30 in milk replacer, soyflour was likely to depress growth rates through poorer palatability of the liquid diet . Keywords: Veal, soyflour, wholemilk, meat, carcass but had little effect on carcass quality. INTRODUCTION There is renewed interest in Victoria in establishing economical year-round production systems for pink veal. This has arisen from the current shortage of medium weight (51-70 kg) carcasses in the wholesale and retail meat trade in Melbourne. Our previous trials (Moran et al. 1987) have shown that feeding systems based on li) l/day wholemilk plus concentrates will produce carcasses with acceptable degree of finish and meat colour by 16 weeks of age. Farm-gate returns for wholemilk in Victoria can vary from less than 15 c/l in spring to over 3ti c/l in winter whereas the equivalent price for milk replacer at the same dry matter (DM) content as wholemilk is about `25 c/l. Therefore wholemilk and/or milk replacer could be fed during year-round veal production systems. The price of milk replacers can be reduced by substituting milk protein with cheaper plant protein. Soyflour has been successfully incorporated into milk replacers provided it is heat treated to remove antitrypsin activity and the It also has an added advantage of calves are at least five weeks old (Roy 1980). containing higher proportions of polyunsaturated fatty acids (YUFA) than milkprotein-based replacers and this will reduce the levels of saturated fatty acids (SPA) in tissues of veal calves fed such diets (Wrenn et al. 1913). This trial compared four liquid diets fed to veal calves, namely wholemilk, wholemilk plus soyflour, milk-protein-based replacer and replacer in which 0.41) of the milk protein was substituted with soyflour protein. MATERIALS AND METHODS Purebred Friesian bull calves were reared on wholemilk plus ad lib concentrate pellets until eight weeks of age. They were then selected on the basis of liveweight (mean of 94.7 kg) and placed in four groups each of ten animals. Between eight and 16 weeks of age, they were given access to ad lib concentrate pellets and trough-fed one of the four diets described in Table 1. The wholemilk contained 42 g/l milk fat, 30 g/l milk protein, t37 g/l solidsThe not-fat and of the total fatty acids, 0.719 were SFA and 0.039 PUFA. yc Tc* *** Kya br Research Insti tute, Kya br am, Vic. 3620 Ruthe rgl en Resea rch In stitut e, Rutherglen, Vic. 3685 Royal Me 1 bourne Ins tit ute of Technology, Melbourne, Vic. 3001 Proc. Aust. Soc. Anim. Prod. Vol. 17 255 commercial milk-protein-based replacer (Veanavite: Bonlac food Ltd.) consisted of 810 g/kg skim milk powder, 170 g/kg tallow and 2c) g/kg vitamins and minerals containing 45.8 g/kg nitrogen (N), 155 g/kg ether extract (EE) and of the total fatty acids, 0.554 were SFA and' 0.023 PUFA. The commercial soyflour (Soyolk: Riverland Vegetable Oils Pty Ltd) was heat treated and contained 70.6 g/kg N, 237 g/kg EE and of the total fatty acids, 0.171 were SFA and 0.602 PUPA. The concentrate consisted of barley (848 g/kg>, full fat soyflour (150 g/kg) plus vitamins and minerals and contained 22.7 g/kg N, 43 g/kg EE, 42 g/kg crude fibre and of the total fatty acids, 0.201 were SFA and 0.587 PUFA. The wholemilk was offered warm each morning and the milk replacers were mixed using warm water. The 7:3 proportion of milk replacer: soyflour was based on recommendations from the manufacturer. Each pen of calves was loose housed on rice hulls in roofed steel yards and had access to water. Concentrate intakes and liveweights were monitored weekly. Half the animals in each pen were slaughtered at 12 weeks and half at 16 weeks of age. Measurements taken on the carcasses and on the 9-lc)-ll rib joints were `Ihe M longissimus dorsi (LD) was described in detail by Moran et a1.(1987). analysed for total lipid content and fatty acids composition using the methods described by Sinclair et al (1982). Data on liveweights and growth rates were analysed by two-way analyses of variance with milk type (wholemilk v milk replacer) and soyflour as fixed factors. Carcass quality and composition and meat quality data were subjected to regression analyses using all values within each diet and adjusting to the mean carcass weight (66.7 kg) along the common slope. Within-diet linear regression coefficients were tested prior to these adjustments but in all cases they were not statistically. different. RESULTS The cool, damp conditions during the trial led to a severe outbreak of Despite regular vaccinations, there were four deaths from enzootic pneumonia. suspected Clostridia diseases. Any calves showing ill thrift were'removed from I the trial between 8 and 12 weeks of age, leaving eight healthy animals per group from which* reliable performance data could be obtained. The morbidity of these disease conditions was high (ie 0.2c)). However, the significant effects of diet on growth rate (see Table 1) confirmed that the remaining calves were unlikely to I be affected at a subclinical level. Intake and performance data are presented. in Table 1 from which it is apparent that calves fed diets including soyflour had th,e poorer growth rates over both age ranges. Intakes of DM from the, soyflour diets were overestimated . becausetherewere occasional residues of undissolved soyflour in the troughs that could not be weighed. The calves fed Diet M had loweltr growth rates than those fed Diet R between8 and 12 weeks (P<&lO).but both groups grew equally well between 12 and 16 weeks of.age. . There were no dietary effects ondressing p.ercent which averaged 51.6. . Dietary effects on carcass measurements were alsonon-significant and the following average values were recorded: conformation score 1.6 ona. .point scale, carcass length .1352mm, leg length -526mm,.forequarter 36.6 kg, .hindquarter 46.7kg, 5-13 ribset 14.7kg. . Other carca.ss and meat quality measures' are presented in Table 2. Meat colour of the.LD is expressed in terms of L value with lower values for darker coloured meat. ,For comparative purposes, L values for meat\ from week old calves. and lot-fed beef steerswere 49.3 and 37.4 respectively (RD. Warner, unpublished data).' Dietary effects on ,weight of kidney fat, retail meat yield, LD area, meat colour *and tenderness 'were all non-significant, The only significant effects. of diet on&b composition, were lower. subcutaneous and intermuscular fat contents in calves fed Diet RS. 256 Proc. Aust. Soc. Anim. Prod. Vol. 17 Intake and performance oi calves fed wholemilk or milk replacer uiets. Table 1. Table 2. Dietary effects w.ere large differences in the most YUFA, the least from wholemilk-fed calves on total lipid contents were non-significant out there EA composition. Calves fed Diet MS produced meat with monounsaturated PA and the highest PUFA/SFA ratio. Meat had the highest levels of WA. Table 2. Carcass and meat quality in calves fed wholemilk or milk replacer diets adjusted to 66.7 Kg carcass weight Results on same line followed fed by different letter differ (PW.i)5). Although calves DISCUSSION the wholemilk grew slower than those fed'the milk- Proc. Aust. Soc. Anim. Prod. Vol. 17 257 protein-based replacer early in the trial, they were able to completely compensate for their lower DM intakes from their liquid diet through greater concentrate intakes between 12 and 16 weeks of age. Subsequently they grew as fast as calves fed the milk replacer. The growth rates of 00th these groups of calves (ie 1.4 kg/day) was superior to those from previous trials (Moran et al. 19871, in which calves fed 10 l/day wholemilk only grew at 1.2 kg/day. The calves fed the soyflour performed poorer than those fed milk-protein diets (Roy 1980) but this may have been further accentuated by the high level of soyflour in their liquid diet. The residues of undissolved soyflour in their troughs are indicative of the poor reconstitution of this particular soyflour in warm water and its poor acceptance by the calves. When fed at 300 g/kg of a milk-proteinbased replacer, there appears to be little economic benefit from soyflour. Including the cost of wholemilk fed to 8 weeks of age (at 15 c/l) and costing the commercial milk replacer at $1.75/kg, the soyflour at 7c)c/kg and the concentrate at ituc/kg, total feed costs to produce a 65 kg carcass were as follows: $79, .$;113, $108 and $125 for Diets M, MS, R and RS respectively. With wholemilk costed at 3&/l, corresponding total feed costs were $151, $198, $146 and $162. Unless the price of milk replacer is markedly reduced, it is unlikely to be used for veal production in Victoria. Diet had little effect on carcass quality or composition. The slower growing calves fed Diet RS had less rib fat and this has been noted in previous trials. Retail yield of meat averaged 0.65 and this is also similar to previous results (Moran et al. 1987). Minimum standards for pink veal carcasses are 2 out of 5 points for carcass conformation and meat colour at 42 L value (R.D. Warner, J.R. Currie and J.B. Moran, unpublished data) hence these carcasses would have been rejected on conformation score and been marginal for meat colour. Meat from ruminant animals is generally rich in SFA and low in PUFA because of hydrogenation of FA by rumenmicro organisms (Sinclair etal. 1982). These calves were still behaving as monogastrics, despite consuming Ox.50 of their dietary DM in the form of concentrate*pellets, because the meat from the soyflour-fed calves had high PUFA/SFA ratios which reflected their higher intakes of PUFA. The inclusion of soyflour in the wholemilk doubled PUFA levels in the meat from o.lC, to c).2& Sinclair et al. (1962) reported PUFA levels of 0.09 in beef and 0.10 in sheep both of which are similar to those in the calves fed non. soyflour diets. . From 'soyflour problems powder do prices. these results, it then appears that the inclusion of 0.30 heat-treated in a milk replacer for group-fed calves could lead to palatability and reduced growth rates. Commercial milk replacers based on skim milk not appear to be economically feasible with current Victorian wholemilk ACKNWLEDGEMENTS The authors are grateful to Ms. R. D. Warner for meat colour measurements The and to Mr. C. Connally for management and feeding of th.e calves. contribution of feedstuffs by Bonlac Food Ltd and Riverland Vegetable Oils Pty Ltd is also ac'knowledged. REFERENCES MCRAN,J.B., WARNER&D. and CURRIE,J.R. (1987). In 'Recent Advances in Anima'l Nutrition in Australia,l987' p.18, editor D.J.Farrell (UNE: Armidale). % ROY, J.H.B. (lUSti). 'The Calf' 4th ed p.,339 (Butterworths : London). SINCLAIR,A.J., SLATTERY,W.J. and O'DEA,K. (1982).J.Sci.Food Agric. 33 : 771. . WRENN, T.R., WEYANT, JR., GORDON, C.H, GOERING, H.K., DRYDEN, Lop., BITMAN, Jo, * EDMONDSON, L,.F. and KING, RL. (1973); J. Anim. Sci. 37 : 1419.