The digestive system of 1-week-old Jersey calves is well suited to digest, absorb, and incorporate protein and energy into tissue growth even when calves are fed a high plane of milk replacer

Abstract

The objectives of the current study were to determine the apparent digestibilities of nitrogen, organic matter, ash, and energy as well as investigate the nitrogen retention of calves fed different planes of milk replacer nutrition during the first week of life. Twelve Jersey calves were blocked by body weight at birth and randomly assigned to either a high plane of nutrition (HPN) or low plane of nutrition (LPN) treatment. The HPN calves were offered 19.2g of dry matter/kg of body weight of a 28% all-milk crude protein and 20% fat milk replacer. The LPN calves were fed 11.6g of dry matter/kg of body weight of a 20% all-milk crude protein and 20% fat milk replacer. All calves were given 3 L of pooled colostrum within 1h of birth after which they were assigned to treatments; no starter was offered during the study. Calves were given 1 d to adapt to their treatments and environment, so calves were 30 to 36 h old at the start of data collection. The study was divided into two 72-h periods. Total collection of feces occurred over each 72 h period, and total urine was collected for the last 24h of each period. Peripheral blood samples were collected at the beginning and end of each period and analyzed for plasma glucose and urea nitrogen concentrations. Data are reported as HPN vs. LPN, respectively. Fecal scores were greater for HPN calves during both periods; however, no difference was found in the dry matter percentage of feces (30.9 vs. 31.9 ± 0.06). No differences were found between treatments in either digestible or metabolizable energy efficiencies, which averaged 93.3 and 83.7%, respectively. A treatment × period interaction was found on the percentage of intake nitrogen retained, in which calves fed the HPN had a greater percentage of intake nitrogen retained during period 1 (87.9 vs. 78.4 ± 1.79%), but was not different from calves fed the LPN during period 2 (85.4 vs. 84.9 ± 1.79%). From these data therefore, we conclude that healthy neonatal calves have the capability to digest and absorb the additional nutrients with a higher plane of nutrition during the first week of postnatal life.

Keywords: calf; digestibility; nutrition.