Growth, nutrient utilization, and body composition of dairy calves fed milk replacers containing different amounts of protein1

Abstract

Male Holstein calves < 1 wk of age were allowed a 2-wk adaptation period after purchase, and then were blocked by BW and assigned randomly within block to either a baseline slaughter group or one of four experimental groups (n = 8 to 9 per group). Treatments were isocaloric milk replacers (12.5% solids) fed at 12% of BW that contained 16.1, 18.5, 22.9, or 25.8% CP (DM basis) from whey protein sources. After a 6-wk feeding period, all calves were slaughtered and the weights and chemical composition of the viscera-free carcasses (VFC; including head, hide, feet, and tail) were determined. Gain of BW (0.38, 0.45, 0.56, and 0.62 kg/d) and gain:feed ratio (0.51, 0.59, 0.71, and 0.78) increased linearly (P < 0.001) as dietary CP increased; rate of change in body length, wither height, and heart girth also increased linearly (P < or = 0.05). Balance measurements conducted during wk 3 and 4 of the experimental period showed that both absorbed N (16.9, 20.0, 25.8, and 30.6 g/d) and retained N (7.6, 9.0, 13.2, and 15.6 g/d) increased linearly (P < 0.001) as dietary CP increased. Retained N as a percentage of absorbed N increased linearly (P < 0.01) as dietary CP increased (44.3, 44.7, 50.7, and 50.9%), whereas biological value was unaffected (71.1, 68.7, 69.5, and 67.3%; P = 0.26). Digestible energy and ME represented 94.5 and 89.7% of intake energy, respectively, and were not affected by dietary CP content. Plasma urea N concentration increased linearly (2.9, 3.3, 4.6, and 6.0 mg/dL) as dietary CP increased. Contents of water (68.2, 69.1, 70.2, and 70.5%; P < 0.001) and protein (19.6, 20.0, 20.0, and 20.2%; P < 0.10) in VFC increased linearly, whereas contents of fat (7.2, 6.2, 5.5, and 5.2%; P < 0.001) and ash (5.1, 5.2, 4.8, and 4.7%; P < 0.02) decreased linearly as dietary CP increased. Trends in visceral tissue composition were similar to those for VFC. The content of water in VFC tissue gain increased, whereas contents of fat and energy decreased, as dietary CP increased. Final VFC energy and gain of energy in VFC were not affected by dietary CP. At similar initial ME intakes, increasing dietary CP (i.e., increasing protein: energy) linearly increased ADG, gain:feed, N retention, and deposition of lean tissue in VFC, demonstrating that diet composition can markedly affect components of body growth in preruminant dairy calves.

Effect of feed intake on heat production and protein and fat deposition in milk-fed veal calves

“…Values for stage 1 are in agreement with earlier reports (Diaz et al, 2001) but are higher than more recent studies (Blome et al, 2003). Values for stages 2 and 3 are consistent with values measured by van den Borne et al (2006) in calves of similar BW.…”

Effects of feeding level and protein content of milk replacer on the performance of dairy herd replacements

“…Influence of treatment on blood protein fractions Blome et al (2003) The range of mean treatment-related PUN concentrations measured in the current study (2.9 to 3.8 mmol/l), although higher than that (1.0 to 2.1 mmol/l) reported by Blome et al (2003) was comparable to those reported by Terosky et al (1997) and Diaz et al (2001) at 2.5 to 2.9 and 3.3 to 4.7 mmol/l, respectively.…”

“…Effects of milk replacer feeding regime Table 5 Summary of studies examining daily liveweight gains during the milk-feeding period Blome et al (2003) and Bartlett et al (2006) in which calves were offered MRs containing up to 260 g CP/kg DM. However, the response to increasing CP content does appear to decline when levels exceed approximately 220 g CP/kg DM as demonstrated by Donnelly and Hutton (1976) and Bartlett et al (2006).…”

“…The aim of this 'accelerated' growth regime is to exploit the high lean tissue growth potential of young calves and promote greater lean growth without fattening. Diaz et al (1998 and showed that feeding a MR of 300 g/kg CP increased lean tissue deposition without fattening, whereas Blome et al (2003) and Bartlett et al (2006) showed that it increased MR protein concentration while maintaining a constant energy density and decreased body fat content. It is important to note that calves in these studies were offered a liquid diet with no supplementary starter concentrates.…”

“…Studies that have examined the long-term effects of levels of pre-weaning nutrition on the performance of dairy herd replacements have frequently had confounding factors in their design. For example, level of feeding was confounded by differences in feeding method in the study by Bar-Peled et al (1997) and by differences in feed type (whole milk compared with MR) in that by Shamay et al (2005), while Blome et al (2003) and Brown et al (2005) used calves with a starting age of 2 to 3 weeks.…”