The effect of intramuscular (IM) injection, per se, on heat (H) production was investigated in ad libitum- and restricted-fed pullets held at normal (21 C) and low (10 C) environmental temperatures. At 21 C IM injection, per se, decreased H-production of ad libitum- and restricted-fed pullets for 2 to 4 hr after injection. This effect was significant (P less than .01) in ad libitum-fed pullets, held at 21 C as well as at 10 C. Thus, when studying the effect of an immune response on the energy metabolism, an effect may be confounded with the effect of the IM injection per se when the measurements are made during the first 2 to 4 hr following injection.

An experiment was carried out with 20 male veal calves to study differences in energy metabolism between pure Dutch Friesian and Holstein Friesian crossbred calves, containing a high proportion of Holstein Friesian genes (0-79). Two metabolizable energy (ME) intakes were given. The effects of genotype and ME intake on live-weight gain and its fat and protein composition were measured by indirect calorimetry and by the total collection of faeces and urine. Energy and nitrogen balances were measured for each calf during the last 5 weeks of the fattening period of 22 weeks.The difference in live-weight gain between the Holstein Friesian crossbreds and the Dutch Friesian calves was not significant but small differences in protein and fat composition of live-weight gain were found. Fat gain was closely related to ME intake (r = 0-95), but the correlation coefficient between ME intake and protein gain was only 0-36. Live-weight gain had a high correlation with protein gain (r = 0-70) but a lower correlation with fat gain (r = 0-29).Veal calves at the end of the fattening period had a declining protein gain as age increased. Calves given a high ME intake (> 2 x maintenance) may require diets containing less than 216 g crude protein per kg diet at the end of the fattening period.The study indicates that Holstein Friesian crossbred veal calves and Dutch Friesian veal calves have similar ME requirements.

Dutch Friesian purebred and Holstein Friesian-Dutch Friesian crossbred veal calves were used to study effects of genotype and feeding level on carcass composition. Carcass analyses were carried out on a total of 56 calves of two genotypes. Calves were reared for 22 weeks and given food dependent on age. From 1 to 16 weeks calves were given the same amount of milk replacer. At week 16, calves were assigned to either a high or low feeding level. Total energy intakes for the two groups were 5062 MJ metabolizable energy (ME) and 5408 MJ ME, respectively. Carcass weight and carcass composition traits showed no significant interaction between genotype and feeding level. Dutch Friesians had higher lean: bone ratios than Holstein Friesian crossbreds (3·85 v. 3·67). Differences between the two genotypes for fat and lean proportions in the carcass were not significant. Average proportions for lean and fat were 653 and 134 g/kg.Differences between the two feeding levels for carcass composition were significant. Calves on the low feeding level had 655 g lean and 131 g fat per kg, while calves on the high level had 645 g lean and 143 g fat per kg.The influence of the dissection technique on the differences in lean and muscle proportion between groups was studied on 18 carcasses using a standardized butcher's method (the Institute of Animal Husbandry (IVO) standard method) and the European Economic Community (EEC) reference method for beef. Average proportion of lean was 640 g/kg by the IVO method and of muscle was 557 g/kg by the EEC method. The difference between the two genotypes for lean proportion was smaller by the' EEC method due to the more complete separation between muscle and fatty tissue. Dutch Friesians had more intermuscular fat than Holstein Friesian crossbreds. Results of the EEC reference method indicate differences between the two feeding levels for fat as well as for protein deposition.