Eighteen lambs (L) and 18 goats (G), 12 weeks of age, were allocated in equal numbers to three diets. The basal (B) diet had no added copper (Cu) while the other two had 30 or 60 mg added Cu per kg dry matter (DM) as CuSO 4 .5H 2 O. Lambs and goats were housed and fed individually. After 67 days, deaths from Cu toxicity occurred only in lambs from groups L-30 (basal diet + 30 mg Cu per kg DM) and L-60 (basal diet + 60 mg Cu per kg DM). The remaining lambs and all of the goats were slaughtered at 91 and 137 days respectively.A decreased food intake and loss of weight were observed in some lambs towards the end of the experiment which appeared to be associated with an approaching haemolytic crisis. The additional dietary Cu had a positive effect on food conversion efficiency only in the early stages of the experiment in both lambs and goats. None of the goats died or lost weight.Plasma Cu concentrations and serum glutamate oxalacetate transaminase and creatine kinase activities were elevated in lambs of groups L-30 and L-60 after 2 months, while in goats the concentrations were in normal ranges during the whole experimental period.Additional dietary Cu increased significantly the Cu concentrations of liver, kidney, muscle, spleen, heart, brain, hair and faeces in both lambs and goats. Additional Cu decreased the fresh and dry liver weights of lambs and the liver to live weight ratio whereas the corresponding values for kidneys were increased. The differences between groups of goats in fresh or dry liver and kidney weights were not significant, though the fresh and dry liver weights tended to be higher in groups G-30 and G-60 compared with those in the group G-B.The amount of Cu stored in the livers of the lambs was six to nine times higher than that of the goats. Differences in Cu storage between lambs and goats may be related to species differences in Cu utilization and hence resistance to Cu toxicity.

No abstract

No abstract

It has been reported that a purified extract from sheep hypothalami inhibited growth hormone (GH) release in rats. This somatotropin-release-inhibiting factor (SRIF), or somatostatin, is a tetradecapeptide and has been prepared synthetically (Brazeau, Vale, Burgus, Ling, Butcher, Rivier and Guillemin, 1973). In addition, _SRIF has been reported t o inhibit the release of other hormones which have major effects upon growth and metabolism such as insulin (Koerker, Ruch, Chideckel, Palmer, Goodner, Ensinck and Gale, 1974), glucagon (Ruch, Koerker, Carino, Johnson, Webster, Ensinck, Goodner and Gale, 1973) and thyroid stimulating hormone (Vale, Rivier, Brazeau and Guillemin, 1974). Furthermore, SRIF has also been shown to be present in large quantities i n the gastrointestinal tract where it controls the release of many gut hormones (Schusdziarra, Zyzhar and Rouiller, 1980). Somatostatin seems, therefore, to be centrally involved in regulating digestion and absorption of food and the subsequent distribution of the absorbed nutrients into tissues within the body. Its removal from the blood circulation by passive immunization increased GH concentrations in plasma in rats (Arimura and Schally, 1976) and prevented decreases in GH concentration as a result of stress (Arimura, Smith and Schally, 1976). Similarly, removal of SRIF by active immunization has been reported to result in higher plasma GH levels in lambs (Varner, Davis and Reeves, 1980; Spencer, Garssen and Hart, 1983b). However, this increase in circulating GH did not appear to have a constant effect in later studies and resulted in inconclusive effects on sheep growth. Laarveld, Chaplin and Kerr (1986) and Spencer, Garssen and Bergstrom (1983a) observed increased growth with improved food efficiency in crossbred and Dutch moor lambs respectively, immunized against SRIF, whereas Varner et al. (1980) reported a significantly lower growth rate in male Columbia lambs and others (Fitzsimons and Hanrahan, 1984; Galbraith, Wigzell, Scaife and Henderson, 1985; Garssen, Welling and Spencer, 1984) concluded that immunization against SRIF did not affect growth in crossbred lambs. It has also been reported that immuno-neutralization of SRIF can lead to enhanced milk production early in lactation n i goats (Spencer and Garssen, 1985).

No abstract