Effects of fish-meal supplementation on performance of overfat lambs fed on barley straw to reduce carcass fatness

Abstract

1989). Effects of sh-meal supplementation on performance of overfat lambs fed on barley straw to reduce carcass fatness. Animal Production, 48, pp 131-138 ABSTRACT The effect of undegradable protein supply was studied in overfat lambs given low-energy diets to reduce carcass fatness. Two trials involving sequential batches of 48 overfat Suffolk x lambs investigated the effects of supplementing an ad libitum straw diet with either 0 or 100 g fish-meal pellets daily for 14-, 28-and 42-day periods. Lambs supplemented with fish meal in trials 1 and 2 lost significantly less weight. Weight losses (g/day) were -2 v. -129 (s.e.d. 26) and -58 v. -188 (s.e.d. 29) respectively. There were highly significant and favourable effects of fish-meal supplementation on carcass weight and composition (recorded in the second trial only). Carcass weight (kg) after 14, 28 and 42 days was 21-8, 20-4 and 18-3 for unsupplemented lambs and 22-4, 21-9 and 21-6 for supplemented lambs; saleable lean (kg) as determined by a commercial boning-out process was 12-1, 11-3 and 10-0 v. 12-7, 12-6 and 12-3 respectively. There were corresponding changes in conformation but fat trimmed off the carcass was not significantly reduced by the dietary treatments. There was, however, a reduction by one-fifth in excess carcass fat (about 0-5 kg) over the period 14 to 42 days on trial, and over the trial as a whole, fat trim fell from an estimated proportion of carcass weight of 0-17 to 012, equivalent to a fall in Meat and Livestock Commission fatness score from 4H to 3L. Results indicated very favourable financial rewards for supplementing diets of overfat lambs with fish meal.

Effects of a high-protein, low-energy diet in finishing lambs: 1. Feed intake, estimated nutrient uptake, and levels of plasma metabolites and metabolic hormones

“…5), similar to the observations by Vipond et al (1989). Absolute straw intake levels were also comparable to the results obtained by these workers.…”

“…There was no significant difference in CP content of refusals between weeks 2, 3, and 4. Vipond et al (1989) reported a very rapid acceptance of the fish meal supplementation by lambs in their experiment; this was not the scenario in our study.…”

“…Thus, protein supplementation did not enhance intake of the straw diet, suggesting an intake limitation caused by energy deficit of the diet. Vipond et al (1989) reported the opposite effect but did not indicate significance of the difference. There was no significant difference in CP content of refusals between weeks 2, 3, and 4.…”

“…Fattet et al (1984) found that lambs given NaOH-treated straw supplemented with fish meal had a positive change in body protein while concomitantly losing body fat. Similarly, Vipond et al (1989) found significantly more saleable lean from lambs supplemented with fish meal vs. non-supplemented lambs on a straw diet. However, both research teams found fat loss to be either equal or lower in the N supplemented groups.…”

“…Lambs assigned to SFM and STR were adapted to the straw diet over a period of one week by gradually replacing the adaptation diet with straw. Lambs on diet SFM did not receive fish meal during the adaptation period, reproducing the design of previous studies (Vipond et al, 1989;Fattet et al, 1984). During the adaptation phase of the study, STR and SFM lambs lost weight while CON lambs continued to gain weight.…”