Effluent from grass silage for finishing pigs

Abstract

SUMMARYA total of 52 individually penned pigs (mean initial and final live weights (LW) of 31·7 and 81·5 kg, respectively) was used in a randomized block experiment at the Agricultural Research Institute of Northern Ireland, Hillsborough, in 1984. The treatments were based on dietary regimes which comprised a control diet in which meal was offered at 86 g dry matter/k W0·75 per day or diets in which silage effluent was substituted for part of the allowance of meal of the control diet at 125, 175, 225 and 275 g/kg on a dry matter basis to give 0·125, 0·175, 0·225 and 0·275 effluent diets. There was also a negative control diet in which meal was offered at 850 g/kg of the rate of feeding of the control diet. Each of these dietary treatments included water available ad libitum. In a further treatment, effluent was substituted for 225 g/kg of the meal allowance of the control treatment on a dry matter basis, but additional water was not offered. The treatment based on the 0·275 effluent diet was omitted from the first four replicates.Some refusals of diet occurred at the higher rates of effluent feeding, with mean refusals of 7, 11 and 21 g/kg, respectively, for the 0·175, 0·225 and 0·275 effluent diets on a dry matter basis. Significant linear and quadratic contrasts (P <0·01) were found for daily LW gain, feed conversion ratio and total liquid intake. The quadratic response curves for daily LW gain and feed conversion ratio had relatively flat peaks, optimum values occurring at concentrations of effluent in the diet of 95 (S.E. 17) and 99 (S.E. 15) g/kg, respectively. From the response curves, performance in terms of LW gain and feed conversion ratio was equal, or superior, to that obtained with the control diet at concentrations of effluent of up to 190 (S.E. 33) and 199 (S.E. 30) g/kg, respectively, but deteriorated at higher concentrations of effluent.Additional water was consumed at all rates of inclusion of effluent. However, from the quadratic equations, the total consumption of liquid was lower with diets containing effluent at up to 161 g/kg of diet than with the control diet.