THE FEEDING OF FERMENTED COLOSTRUM TO NEONATAL CALVES. IV. EFFECT OF ENERGY SUPPLEMENTATION OF FERMENTED COLOSTRUM ON PROTEIN UTILIZATION

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Abstract
Twenty-four Holstein calves were fed fermented colostrum (Streptococcus lactis) treated with sorbic acid, from 4 through 24 days of age to study the effects of increasing the ratio of calculated digestible energy (DE, kJ) to digestible protein (DP, g). Approximate ratios (kJ DE/g DP) studied were 64.4, 82.8, 99.6 and 126.8, which were obtained by adding increasing amounts of a mixture of cerelose (46.4%) and a fat concentrate (53.6%) to the basal colostrum diet. Recorded data included daily feed intake, body temperature, fecal characteristics, weekly body weights and analyses of colostral pH and titratable acidity. At the beginning and end of the experiment, colostrum was analyzed for protein, NPN, fat, lactose and ash. Blood serum samples taken at day 21 were analyzed for glucose and urea. A digestibility study was conducted between days 14 and 17. There was a significant (P < 0.05) increase in gain with each increment of DE (15.9, 103.2, 174.6 and 321.4 g for DE/DP ratios of 64.4, 82.8, 99.6 and 126.8, respectively) and improvement of protein: gain (g/1000 g) ratio (9.095, 1.355, 849 and 444, respectively). Blood urea levels were being negatively correlated (r = −0.67) with DE intake and positively correlated (r = 0.94) with surplus DP. There was a tendency for a reduction in digestibility of fat and protein with increasing supplementary energy. The reduction was significant (P < 0.05) for total solids and lactose equivalent. The equation Y (DE) = 8326 + 12.3 x (ADG) was constructed to describe the relationship between the daily intake of DE (kJ) and ADG (g). The maintenance requirement of the nonruminating calf was estimated as being 176 kJ DE/kg of liveweight and 12.36 kJ of DE required per gram of gain. Energy supplementation of fermented colostrum improved calf growth and decreased blood urea nitrogen but increased the incidence of loose feces. Key words: Digestibility, energy requirements, SUN, energy: protein ratio