Effect of the β-adrenergic agonist cimaterol and dietary protein level on fat young sheep given diets containing submaintenance levels of dietary energy

Abstract

Thirty Suffolk cross wether sheep aged about 12 months and weighing 57 kg on average were used. They had been given previously a high energy diet to produce a fat body condition and average condition score of 3-7. Animals 'were allocated to an initial slaughter group (IS) or to four dietary treatment groups (UL, UH, CL and CH) based on sugar-beet feed (L) or white-fish meal (H) supplemented with chopped straw and pelleted, without (UL and UH) or with (CL and CH) the (5-adrenergic agonist cimaterol, to provide an estimated 20 g (L) or 130 g (H) rumen undegradable protein per kg dry matter (DM). The sheep were offered 0-3 kg of the appropriate pelleted diet in addition to 200 to 400 g of chopped barley straw to provide proportionately 0-7 of the estimated metabolizable energy requirement for maintenance and, where appropriate, 2-5 mg cimaterol per day. Comparisons were made for the main effects of dietary protein intake and cimaterol and interactions between dietary protein and cimaterol. The animals on dietary treatments were slaughtered after 49 days. The animals exhibited variable reductions in live weight and weights of carcass and non-carcass components in comparison with the IS group and in response to restricted dietary energy intake. The only effect due to the elevated dietary protein provision was a smaller loss in live weight compared with the low protein diet. In contrast, compared with responses recorded in its absence, treatment with cimaterol resulted in significantly greater values for weights of cold carcass, cross-sectional area o/m. longissimus dorsi and weights of DM, crude protein and ash in the carcass with significantly smaller weights for raw fleece. In comparison with the IS group, significantly smaller changes due to cimaterol were recorded for the weights of carcass crude protein and ash. Cimaterol treatment significantly increased the weight loss of fat in the carcass and in the perirenal and retroperitoneal, but not omental, depots as components of fleece-free non-carcass fat which was also significantly reduced in total. Interactions suggested that losses in carcass weight and DM in the presence of cimaterol were less and gains in carcass protein and ash greater, on the high than on the low protein diet. The results suggest that under conditions of energy undernutrition cimaterol may induce smaller losses or larger gains in carcass but not non-carcass, crude protein at the expense of fat depletion in carcass and non-carcass fat depots.

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

“…Ortigues et al (1990) measured comparable effects of fish meal supplementation on BUN levels in heifers under a similar regimen. Galbraith et al (1997) found a difference in BUN between fish meal supplemented and unsupplemented treatments similar to that observed in the present study. Lindberg and Jacobsson (1990) found significant effects on BUN levels of both energy and N concentration of intragastric infusates in lambs of comparable age and size.…”

“…These observations do not support an enhanced use of endogenous fuels for protein accretion under high N supply. In a similar experiment, Galbraith et al (1997) did not find enhanced protein accretion in lambs, but rather a tendency toward lower peripheral fat mass and higher carcass fat losses for N supplemented growing lambs, compared to unsupplemented lambs.…”

“…Reilly and Ford (1971) reported a significant correlation between total glucose production rates and daily protein intake in sheep. Galbraith et al (1997) did not find a difference in plasma glucose Fig. 4.…”

“…ingly, the two straw-fish meal treatments in their experiments were estimated to have been consumed at 307 and 488 kJ/kg BW 0.75 , respectively. Galbraith et al (1997) estimated an energy uptake in their study of 188 kJ/kg BW 0.75 without reporting intake data. Fattet et al (1984) calculated an effective degradability of fish meal in their study of 0.416; when using their estimated level of energy intake of animals used for experimental determination of degradability, the equation relating digestibility to outflow rate presented above yields an effective degradability of 0.481.…”

Influence of dietary zilpaterol hydrochloride on feedlot performance, carcass traits, chemical composition of longissimus muscle, and plasma metabolites of castrated male goats

“…In nonruminant species, zilpaterol increased plasma glucose levels within 72 h, but significantly decreased glucose levels after 14 days (20). As in the present study, Galbraith et al (21) recorded significant reductions in plasma-free fatty acids at day 9, but observed an increase in plasma glucose concentration at day 49 in lambs treated with cimaterol. Likewise, Kim et al (22) observed significant increases in the plasma concentrations of fatty acids and triglycerides following supplementation with 10 ppm of cimaterol.…”