Growth and body composition of dairy calves fed milk replacers containing different amounts of protein at two feeding rates1

Abstract

Previous research has demonstrated that increasing the CP concentration from 16 to 26% in milk replacers fed to male preruminant dairy calves at 1.5% of BW (DM basis) daily resulted in increased ADG, G:F, and deposition of lean tissue. However, the effects of dietary CP would be expected to vary depending on ME intake. Here, male Holstein calves < 1 wk old were used to determine the effects of feeding rate and CP concentration of isocaloric, whey protein-based milk replacers on growth and body composition. After a 2-wk standardization period, calves were assigned randomly to an initial baseline group or to treatments in a 2 x 4 factorial arrangement of feeding rate (1.25 or 1.75% of BW daily, DM basis) and milk replacer CP concentration (14, 18, 22, or 26% of DM). No starter was offered, but calves had free access to water. After a 5-wk feeding period, calves were slaughtered and body composition was determined. Increasing the feeding rate increased (P < 0.05) ADG, G:F, empty-body gains of chemical components and energy, the percentage of fat in empty BW gain and in the final empty body, and concentrations of IGF-I and insulin in plasma. Increasing the feeding rate decreased (P < 0.01) percentages of water and protein in the empty body and decreased urea N in plasma. Increasing dietary CP concentration linearly increased (P < 0.05) ADG, body length, heart girth, and gains of water and protein but linearly decreased (P < 0.05) fat gain. As dietary CP increased, fat content in empty body gain decreased, and water and protein increased. Increasing CP concentration increased (quadratic, P < 0.02) G:F, with greatest efficiencies for calves fed 22% CP. Gross energetic efficiency (retained energy:intake energy) was greater (P < 0.05) for calves fed at 1.75% of BW daily. Efficiency of dietary protein use for protein gain was greater for calves fed at 1.75% of BW daily but was not affected by dietary CP. The ratio of protein gain to apparently digestible protein intake above maintenance decreased as dietary CP increased. Interactions (P < 0.05) of feeding rate and CP concentration for gains of water and protein indicated that when dietary CP was 26% the ME supply limited protein use by calves fed at 1.25% of BW daily. Body composition of preruminant calves can be markedly altered by manipulating the protein to energy ratio in milk replacers. These dietary effects on body composition and growth are not predicted by current NRC standards.

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

“…The flowing agent was responsible for the small increase in average ash content in the current study compared with that reported in other studies (e.g. Bartlett et al, 2006). Drinking water was available at all times throughout the study.…”

“…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.…”

Feeding dried distillers grains with solubles to lactating beef cows: impact of excess protein and fat on cow performance, milk production and pre-weaning progeny growth

“…It should be noted, however, that intake of Dried distillers grains in lactating beef cows maternal diets by calves during the neonatal treatment period in the current experiment was possible, and thus could have contributed to differences in BW. However, studies with milk replacer in dairy calves suggest that increasing protein increases calf BW and protein deposition, although protein may only be beneficial if energy supply is adequate (Bartlett et al, 2006). A portion of nitrogen requirements for nursing calves can be met by urea as early as 6 weeks of age (Brown et al, 1956), thus increased MUN in DDGS fed cows may have been responsible for increased growth rates of progeny.…”

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

“…Several studies involving different FL have been conducted during the last decade in veal calves using the comparative slaughter technique (Gerrits et al, 1996;Diaz et al, 2001;Bartlett et al, 2006). Nevertheless, little attention has been paid to the dynamic change of the response of the calf over -E-mail: jean.noblet@rennes.inra.fr short periods of time.…”