The distribution of meat in pink veal carcasses as influenced by carcass weight, breed and diet.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 19 THE DISTRIBUTION OF MEAT IN PINK VEAL CARCASSES AS INFLUENCED BY CARCASS WEIGHT, BREED AND DIET J.B. MORANA and J. R. CURRIE B *Dept of Food and Agriculture, Kyabram Research Institute, Kyabram, Vic. 3620. BDept of Food and Agriculture, Rutherglen Research Institute, Rutherglen, Vic. 3685. SUMMARY Forty bull calves, 20 purebred Friesian and 20 beef x Friesian, were reared either on whole milk and concentrates or were early weaned onto concentrates and low quality hay and then slaughtered at either 12 or 16 weeks of age. Carcass sides from 24 calves were jointed, dissected into commercial veal cuts and trimmed of excess fat. Composition of carcass tissues were measured and selected hindquarter cuts were grouped as the expensive cuts. There was no effect of hindquarter conformation on the distribution of meat within the carcass. Crossbred carcasses had less bone and more fat trim. Early weaned calves produced carcasses with more meat and expensive cuts and less fat trim than did milk-fed calves. Production costs for pink veal can be reduced by weaning calves off milk at 6 weeks of age and using purebred rather than more expensive crossbred dairy calves. Keywords: veal, carcass, conformation, breed, diet. INTRODUCTION Pink veal is a new meat product recently developed in Victoria. Markets demanded low cost, heavier veal carcasses (50-70 kg) rather than the lightweight carcasses (25-35 kg) readily available from very young, ` bobby' calves excess to dairy herd requirements. The major difference between ` pink' and socalled ` white' veal calves is their diet, in that white veal systems rely solely on milk to minimise dietary iron intakes whereas pink veal calves are fed concentrates as well as milk (Moran 1990). Profitability of pink veal production can be increased by reducing milk intakes in calves, so long as this does not adversely affect calf performance, carcass quality and consumer acceptability of the end product. Veal is usually sourced from purebred Friesians bull calves. They are often considered unsuitable for meat production because of their ` poor' hindquarter conformation which can lead to carcasses lacking in muscularity and yield of high priced cuts (Johnson 1984). The use of traditional beef sires, such as Hereford or Angus, over dairy cows should improve conformation in their progeny and hence their acceptability as veal calves. In one of a series of trials at Kyabram evaluating different management systems for pink veal (Moran et al. 1991), we compared purebred and crossbred dairy calves fed either milk-based or early weaning diets. This paper reports the effect of breed and diet on the distribution of meat and tissue composition in pink veal carcasses ranging in weight from 34 to 96 kg. MATERIALS AND METHODS Twenty purebred Friesian and 20 beef x Friesian week-old bull calves were purchased from calf auctions. The crossbreds were mainly Herefords with several Angus and Charolais-sired calves. Calves were blood sampled for maternal antibody levels, which were all in the acceptable range (Moran 1990) and allocated to one of 4 pens (each of 10 calves) balanced for age, liveweight and, within the crossbred pens, by breed types. One pen of purebred and one of crossbred calves were fed whole milk plus concentrates until slaughter while the other purebred and crossbred pens were early weaned at 6 weeks of age then fed concentrates plus low quality hay until slaughter. Calves were vaccinated against Clostridia at 7 and 9 weeks of age. Each pen of 10 calves was loose-housed on rice hulls in roofed, steel yards. Animals were individually fed milk from buckets, to ensure all calves consumed their allocated quantities of milk, and had continual access to water, concentrates and hay, where appropriate. Each milk-fed calf received a maximum of 10 L milk/day while each early weaned calf was offered no more than 4 L milk/day. Concentrate and hay were offered ad Zibitum. The concentrate pellets for the milk-fed calves (15.4% crude protein, 72.0% digestibility) comprised barley and full-fat soy flour while those fed to early weaned calves (16.3% protein, 73.5% digestibility) consisted of cereal grain, protein supplements, limestone rumen buffer plus a vitamin-mineral premix. Half the calves in each pen were slaughtered at 12 weeks and the remainder at 16 weeks of age. Following slaughter, hindquarter conformation was assessed using a score from 1 (concave, thin musculature) to 5 (convex, thick musculature), with intervals of 0.5 units. Chilled carcass sides from 3 calves were randomly selected for detailed carcass dissection from each 5 animal slaughter group. 65 Proc. Aust. Sot. Anim. Prod. Vol. 19 Carcass sides were again scored for conformation then broken into joints, as described (1986). The same experienced butcher dissected each joint into commercial cuts which were excess fat. The fillet, butterfly, medallion, topside, round, silverside and rump cuts from the were grouped to form the ` expensive cuts' . Carcass data were analysed by a stepwise multiple regression, using the GENSTAT s package, in the following model: by AMLC trimmed of hindquarter statistical where Y is the weight of each carcass joint, of trimmed carcass meat, bone or fat trim or its content in the total side weight, SWT is side weight, CON is conformation score, BR is a pseudovariate for breed (Friesian -1, crossbred +l) and DI is a pseudovariate for diet (milk -1, early weaning +l). The significance of including each variable, factor (BR and DI) and interaction was determined by reductions in residual mean squares in corresponding analyses of variance. Values (and standard errors) for each dependent variable were predicted at 30 or 40 kg side weights by GENSTAT using models containing only significant (P < 0.05) regression coefficients. RESULTS The purebred and crossbred calves had similar intakes, growth rates and dressing percentages (Moran et al. 1991). Carcass weights at 12 weeks were higher (PcO.01) for the milk-fed calves (66.7 v. 46.1 kg) but not significantly different by 16 weeks of age (79.3 v. 73.1 kg). Milk-fed calves had higher (PcO.01) dressing percentages (55.7 v. 51.8%). Side weights ranged from 16.0 to 45.6 kg while conformation scores varied from 1.0 to 3.0. There were no breed or diet differences in conformation score which averaged 1.98 (s.d.=0.28) in purebred and 1.94 (s.d.=0.52) in crossbred calves. The weights of carcass joints and trimmed meat and the composition of carcass tissues, predicted at 30 and 40 kg side weight, are presented in Table 1. Regression coefficients for side weight were significant (PcO.05) in each model except for percentage fat trim. The regression coefficient for conformation score was significant only for fillet weight while the interaction between side weight and conformation score was significant for weights of carcass loin joint and fillet. Table 1. Mean (+ s.e.) weights of carcass joints and trimmed carcass meat (kg) and mean (+ s.e.) composition of carcass tissues (%) predicted at 30 and 40 kg side weight Significant factors and their interactions in each model for comparing breeds (BR) and diets (DI) and their partial regression coefficients (b) are also included 66 Proc. Aust. Sot. Anim. Prod. Vol. 19 Crossbred carcasses had heavier forequarters and more fat trim while there were significant interactions between breed and diet for weights of meat and bone and for percentage carcass bone. When comparing diets, carcasses from the early weaned calves had the heavier hind leg primal joint, heavier fillet and hind leg meat, more trimmed meat and expensive cuts and less fat trim. DISCUSSION The stepwise regression analyses were used to test for differences between treatments rather than to predict carcass tissue weights and composition and hence only selected coefficients were used in each model. Although purebred and crossbred calves did not differ in hindquarter conformation in this study, we have recorded higher conformation scores in Hereford x Friesians than in purebred Friesians in a previous trial (Moran et al. 1991). There was little difference between breed types in growth rate, dressing percentage or carcass meat yield. The major breed difference was in tissue composition in that the crossbreds had more fat trim and, when early weaned, less carcass bone. Carcass conformation had little effect on meat distribution. In older animals, this has often been attributed to the confounding influence of fat cover on conformation score. In fact, Johnson (1984) noted conformation to be negatively related to meat yield, a result brought about primarily by overfatness. As veal carcasses have minimal fat, which in this trial did not vary with carcass weight, the poor association between conformation and meat yield, particularly with regards yield of expensive cuts, casts doubt on its usefulness as a measure of carcass quality. Despite heavier carcass weights at 12 weeks of age and higher dressing percentages in the milk-fed calves, the more expensive diet did not improve percentage carcass meat. In a previous trial, we also recorded higher levels of fat trim in milk-fed calves (Moran et aZ. 1991) but noted fat trim to increase with carcass weight. However in that trial, we found no effect of carcass weight on percentage fat trim in calves fed only on concentrates. Of greater economic importance in this study, was the fact that milkbased diets actually reduced the proportion of expensive cuts in the carcass. When assessing meat samples from these carcasses for veal quality attributes, Warner and Currie (unpublished data) found meat colour, intramuscular fat content and tenderness to be similar in the meat from milk-fed and early weaned calves. Although the early weaned calves returned less per carcass, because of their lower dressing percentage, this was partly offset by their higher content of expensive cuts and their similar consumer acceptability. The fact that live animal performance and carcass and meat quality in calves weaned off milk at 6 weeks of age did not greatly differ from those in calves fed milk to slaughter, shows that feed costs for veal production can be markedly reduced. Moran et aZ. (1991) conducted detailed economic appraisals of these two particular production systems, based on carcass returns of $4-5O/kg carcass weight and throughputs of 5 calves/week. They calculated operating profits for the early weaned calves of $84/calf compared to only $19/calf when fed 10 L milk/day to slaughter. With pink veal carcasses returning $5/kg carcass weight, operating profits increased to $119 and $54/calf respectively (Moran 1990). Any improvements in yield of high-priced cuts in the early weaned calves was an added bonus. Further cost reductions are possible as meat yield in purebred dairy calves and beef crossbreds were similar and the latter can cost an additional $20-30 to purchase as week old calves. ACKNOWLEDGMENTS The authors thank Colin Connally and the Kyabrarn field staff for managing the calves and Barry Warren and Gervaise Gaunt for carcass dissections. The work was partly funded by the Meat Research Corporation. REFERENCES AMLC (1986). ` Handbook of Australian Meat, Sect 2: Veal' (AMLC: Sydney.) . JOHNSON, E. R. (1984). Proc. Aust. Sot. Anim. Prod. 15: 396-9. MORAN, J. B. (1990). ` Growing Calves for Pink Veal' Tech. Rep. 176 (DARA, Melbourne.) , MORAN, J. B., HOPKINS, A. H. and WARNER, R. D. (1991). Outlook on Agric. 20: 183-90. 67