Nitrogen utilization, preweaning nutrient digestibility, and growth effects of Holstein dairy calves fed 2 amounts of a moderately high protein or conventional milk replacer

Abstract

Studies have shown that calves fed milk replacers (MR) with crude protein (CP) concentrations greater than 20%, as typically found in conventional MR, have higher dry matter intakes (DMI) and greater average daily gains (ADG) but consume less starter, which can lead to stress during weaning and reduced rumen development. The greater amount of CP being fed to preweaned calves may alter their nitrogen (N) balance, and excess N may be excreted in the urine. The objective of this study was to determine N utilization in preweaned calves fed diets varying in the amount of CP and MR fed. This study used 24 newborn dairy heifer calves blocked by birth and randomly assigned to 1 of 3 treatments: (1) 446g dry matter (DM) of a conventional MR (CON; 20% CP, 20% fat), (2) 669g DM of a moderately high protein MR (moderate; MOD; 26% CP, 18% fat), or (3) 892g DM of a moderately high protein MR (aggressive; AGG; 26% CP, 18% fat). All calves had ad libitum access to starter and water. Both MR and starter were medicated with decoquinate. During weaning (d 43-49), the morning MR feeding ceased. On d 50, all MR feedings ended; however, starter and water intakes were continuously recorded until d 56. At 5wk of age, urine was collected using urinary catheters for 3d and chromium oxide was administered by bolus at 2g/d for 7d to estimate N efficiency. Calves fed MOD and AGG had similar starter intakes, feed efficiencies, and ADG, with the combined treatments having reduced starter intakes (258 vs. 537g/d), greater ADG (674 vs. 422g/d), and improved feed efficiency (0.57 vs. 0.45 gain:feed) compared with CON calves preweaning. However, DMI and water intake were similar across all treatments. Results from the N utilization phase showed that MOD and AGG treatments had similar but lower N efficiency compared with CON calves (45.5 vs. 52.7%). This could be due to MOD- and AGG-fed calves having greater urine volume and thereby, greater combined urine N output compared with CON calves (17.6 vs. 12.1 g/d). In summary, feeding >0.66kg (DM) from a 26% CP MR increased ADG and improved feed efficiency during the preweaning period but reduced starter intake and lowered N efficiency.

Effects of amount of colostrum replacer, amount of milk replacer, and housing cleanliness on health, growth, and intake of Holstein calves to 8 weeks of age

“…Sample size was calculated based on the experience of previous studies (Chapman et al, 2016(Chapman et al, , 2017 using similar procedures at the same facility and expecting a 90% probability to detect a ≤200 g/d difference in ADG with SE of 100 g/d at P < 0.05. Data were analyzed using the MIXED procedure in SAS (version 9, SAS Institute Inc., Cary, NC).…”

“…Nutrients in MR are typically more digestible and are used with greater efficiency than nutrients in starter. Other studies (Diaz et al, 2001;Khan et al, 2007b;Chapman et al, 2017) reported greater feed efficiency in calves fed more milk or MR. However, other studies (Khan et al, 2007a) reported no difference in feed efficiency in calves fed more milk before weaning.…”

Effect of different fat and protein levels in calf ration on performance of Sahiwal calves

“…Nitrogen intake (NI), N voided through faeces, urine and total N outgo remained unchanged during experimental trial. Chapman et al [22] observed no differences in N intake in Holstein dairy calves fed with high protein milk replacer. The N absorption did not alter with various levels of fat and protein.…”

“…This improvement in digestibility of DM, OM, and CP could be due to increase in quantity of better quality nutrients with increase in protein levels of calf starter. Chapman et al [22] reported that calves fed with milk replacer (26% CP, 18% fat) had greater nutrient digestibility for DM, OM and tended to be greater for CP digestibility than the control groups (20% CP, 20% fat). In contrary, feeding of calves with MR (27% CP and 17% fat) at pre-weaning stage leads to decreased OM digestibility of 11% at post-weaning stage [23].…”

The role of colostrum for the newborn thermogenesis and feeding strategies for calves raised in low temperatures

“…There was no difference between NC and HRTS preweaning for glucose concentrations, supporting previous studies (Omidi-Mirzaei et al, 2015;Chapman et al, 2017). However, plasma glucose was greater in calves HRAS from birth trough week 7 compared to calves fed NC (P = 0.05), possibly as a result of greater liquid feeding and the greater starch intake by cracked corn provided as the main ingredient in AS group until week 4 ( Figure 5).…”