The effect of fishmeal supplementation of a straw-based diet on growth and calorimetric efficiency of growth in heifers
British Journal of Nutrition
Thirty-two 160 kg dairy heifers were used to measure the effects of increasing dietary protein content on growth and heat production. A basal diet containing (g/kg) 550 sodium hydroxide-treated straw, 220 barley, 220 sugarbeet pulp and 10 urea was offered with 0,76 and 152 g fishmeal/kg dry matter of the basal diet (FO, F1 and F2 levels respectively). The three diets were each given at two levels of feeding (low, L; high, H): 57.6 g/d per kg metabolic body-weight (Wo7') for the LFO diet and 747
... he LFO diet and 747 g/d per kg Wo7' for the HFO diet. Apparent digestibility of the diets increased in response to the addition of fishmeal. Mean dry matter digestibility values were 0.67, 0.67, 0.69, 0.66, 0.68 and 069 and those for acid-detergent fibre digestibility were 0.60,0.63,066,0.58,060 and 0.65 for diets LFO, LF1, LF2, HFO, HFl and HF2 respectively. Nitrogen retention increased in response to both fishmeal and feeding level. Live-weight gains were 170, 296,434 g/d for the LFO, LFl and LF2 diets and 468,651 and 710 g/d for the HFO, HF1 and HF2 diets respectively. There were significant effects of increasing the plane of feeding and the level of fishmeal in the diet on live-weight gain. Dietary effects on live-weight gains were accompanied by increases in mean energy retention of 23,45,82,94,160 and 152 kJ/d per kg WO" for diets LFO, LFl, LF2, HFO, H F l and HF2 respectively, but no definite evidence was obtained that dietary supplementation with fishmeal modified the efficiency of utilization of metabolizable energy for growth.