Effect of inclusion of protected and unprotected tallow in the supplement on the performance of lactating dairy cows

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Abstract
Three concentrate mixtures were compared in a replicated 3 × 3 Latin square feeding trial with cows in early lactation to evaluate the effect of inclusion of tallow. The concentrates were based on barley and soya bean meal (223 g crude protein per kg dry matter) with either no tallow addition (control group) or with the addition of a protected tallow premix (0·75 spray-dried formaldehyde-treated tallow, 0·25 casein) or an unprotected tallow premix (0·75 spray-dried tallow, 0·25 casein), both added at 138 g/kg. Each concentrate was given at a rate of 8 kg per cow per day and silage was offered ad libitum. The inclusion of unprotected tallow in the concentrate did not significantly change milk yield, fat concentration, lactose concentration or live weight compared with those in the control group. The inclusion of the protected tallow supplement resulted in significantly higher yields of milk (22·9 kg/day), fat (0·95 kg/day) and lactose (1·05 kg/day) compared with those of the control group (21·3 kg/day, 0·79 kg/day, 0·95 kg/day), whilst milk protein concentration was significantly reduced. A digestibility trial with steers showed that, when hay was given with the diets, inclusion of tallow in the concentrate significantly increased the digestible and metabolizable energy concentration of the diets compared with the control diet, but dry matter, energy and fibre digestibility was reduced.