1987). The effects of dose and method of administration of biosynthetic bovine somatotropin on live-weight gain, carcass composition and wool growth in young lambs. ABSTRACT Exogenous bovine pituitary somatotropin (GH) can influence markedly body composition in fattening lambs. However, neither the effects of biosynthetic somatotropin nor the effects of dose and method of administration have been reported. Fifty Dorset-cross lambs (female and castrated male) were given concentrate ad libitum and treated between 10 and 22 weeks of age with biosynthetic bovine somatotropin either dissolved in buffer and injected subcutaneously (s.c.) in proportion to body weight (0-025, 0-1 or 0-25 mg/kg per day), dissolved in buffer and continuously infused s.c. (0-1 mg/kg per day) or suspended in olive oil and injected s.c. (0-1 mg/kg per day), and compared with 10 untreated control lambs. Somatotropin had little effect on live-weight gain (controls = 228 g/day; final live weight 37 kg), food intake and food conversion efficiency, and only marginally increased the weight of muscle and bone dissected from the shoulder joint. The weights of the major fat depots in the abdominal cavity and of fat dissected from the shoulder joint were linearly related to dose of somatotropin (P < 0-001). Lambs given the highest dose had less visceral fat (1-18 v. 2-84 kg; P < 0-001) and proportionately less fat (285 v. 374 g/kg; P < 0-001) and more muscle (542 v. 447 g/kg) and bone (172 v. 149 g/kg; P < 0-001) in the shoulder joint than control lambs. There was a positive curvilinear relationship (P < 0-01) between clean wool growth (mid-side patch sample) and dose; lambs injected daily with 0-1 mg somatotropin per kg grew one-third more wool than control lambs. Method of administration affected plasma somatotropin profiles but had no significant influence on any of the responses measured. The anabolic actions of somatotropin may have been limited in this experiment by a low sodium concentration in the diet. It is concluded that the lipolytic/anti-lipogenic effect of somatotropin can occur in the absence of conditions conducive to the stimulation of muscle protein deposition and that the response is dose dependent but not influenced by method of administration of the hormone.
Masham ewes were mated at three stages of the breeding season, early (15 September to 20 October), mid (20 October to 24 November) and late (15 December to 19 January), at two different body condition scores, 4 and 2, for 3 successive years. The mean scores achieved for body condition 4 were 3-6, 3-7 and 3-9 for early, mid and late respectively and for body condition 2 were 2-4, 2-3 and 2-2. In the late lambing flock more ewes were marked by vasectomized rams and less ewes were barren than in the early and mid flocks. The ewes in higher body condition at mating had significantly more triplets and fewer singles, and a higher lambing percentage (183 versus 165). This effect of body condition on litter size distribution was significant at each time of mating, with the ewes at the late mating producing significantly fewer triplets and more singles; this difference was caused by a reduction in the performance of the body condition 4 ewes in the late group. Young ewes in the body condition 4 group produced significantly fewer triplets and more singles than the mature ewes in the same body condition group, but at the lower body condition age had no effect on litter size distribution.
Daily injections of bovine pituitary somatotropin (growth hormone) can markedly increase growth and muscle deposition in fattening lambs, although the optimal dose range for these effects is not known.This experiment was designed to assess the anabolic and lipolytic activities of biosynthetic somatotropin (produced by genetically-modified bacteria) in fattening lambs, and to determine the effects of dose and method of administration.Dorset Down x Finn-Dorset lambs were individually penned, fed a barley/soyabean meal diet ad libitum (C.P.=155g/kg DM) and allocated to one of six treatment groups, each containing 5 ewe and 5 wether lambs, such that each group had the same initial mean live weight (18 kg). Between 10 and 21 weeks of age, the lambs of each group received one of the treatments shown in Table 1, comparing 3 doses of somatotropin (0.025, 0.1 or 0.25 mg/kg live weight), dissolved in bicarbonate buffer and injected subcutaneously once each day, with the intermediate dose (0.1 mq/kg/day) given by continuous subcutaneous infusion or by daily subcutaneous injection as a suspension in olive oil.
The different feeding treatments, which affected the fatty acids profile, did not affect the sensory quality of the meat as found by tasting panels. The tasting panels rated samples of meat from 1-7 for aroma, flavor, hardness and juiciness. There were no statistically significant differences between the groups in neither of the above parameters. Intake of concentrates by S kids increased from a mean 850 g/day during gain from 21-29 kg to 1 130 g/day in the interval from 37-45 kg but intake relative to liveweight decreased from 35 to 28 g/kg, a little lower than those of lambs on a similar diet. The growth rate only declined very slightly over the three growth intervals but conversion efficiency decreased by 28 %. The A x S kids had lower intakes, growth rates and efficiencies of conversion than S kids.
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