Utilization of fish protein hydrolysates in milk substitutes for lambs

Abstract

SUMMARYMale and female (Suffolk × (Finnish Landraee × Dorset Horn)) lambs were used in three experiments to examine the replacement of milk by undried and dried fish protein hydrolysates (FPH), a mixture of lard and coconut fat, and partially hydrolysed starch (Protamyl 110). The animals received the experimental diets from 1 week of age in Expts 1 and 2, and from 4 weeks of age in Expt 3. They were given the diets in eight equal feeds (i.e. every 3 h) from an automated teat bar system. The level of feeding was 1·046 MJ/kg0−76/day. Experiments 1 and 2 lasted for 35 days, during which live-weight gain and food conversion ratios were recorded and at the end the digestibility of N, dry matter and starch was determined. Experiment 3 consisted of three small digestibility trials.In Expt 1, the replacement of milk protein with undried FPH and of milk fat with lard plus coconut fat had no significant effects on live-weight gain, food conversion ratio or nutrient digestibility. Somewhat lower gains for the lambs given the FPH than those given milk protein were observed during the first 15 days of the experiment. Apparent digestibility of milk protein and milk fat was 95 and 99% while that of PFH and lard plus coconut fat was 94 and 96% respectively. The replacement of milk fat with lard and coconut fat caused some reduction in live-weight gains and nutrient digestibility. Lactose was completely replaced by protamyl both in diets based on milk protein or FPH with no effect on live-weight gains or food conversion ratio.Apparent digestibility of fish protein was not affected by the drying process. Fat digestibility of diets containing undried or dried FPH ranged from 46 to 98% according to the type of emulsifier used. The results are discussed in relation to published data concerning the problems associated with the use of fish protein in milk replacers.