I. Kale (Brassica oleracea) and ryegrass (Lolium perenne)-clover (Trijolium repens) pasture, grown under similar soil conditions, were grazed in the vegetative state by growing lambs of 23.6 kg initial live weight for 24 weeks. The kale and pasture contained respectively 20 and 270pg iodine/kg dry matter (DM). The kale also contained 8 pmol total glucosinolates/g DM and 11.5 g S-methyl-L-cysteine sulphoxide (SMCO)/kg DM, both of which were nondetectable in the pasture diet.2. Intramuscular injections of I (475 mg) were given during weeks 1 and 12 to half the forty-eight lambs grazing each forage. Wool growth, live-weight gain and cytochrome oxidase (EC 1 .9.3.1) activity of biopsied hind-limb muscle were measured at 6-week intervals. Jugular blood samples were removed every 6 weeks for the determination of haematological factors and serum thyroid hormone concentrations. All animals were slaughtered at the end of the experiment and thyroid weight, thyroid I content, and the weight and cytochrome oxidase activity of heart muscle determined.3. Serum concentrations of thyroxine (T,) increased from 20 to 48 nmol/I during the 24 weeks that control lambs grazed ryegrass-clover pasture. I supplementation increased the concentration and total amount of I in the thyroid gland and increased serum T, concentration, but did not affect any other values measured in the lambs grazing the pasture herbage. Serum concentrations of triiodothyronine (T,) were stable at 2 nmol/l for both groups.4. Control lambs grazing kale for 24 weeks showed marked thyroid enlargement and depletion of thyroid I. By week 6, serum T, and T, concentrations had declined to 2-5 nmol/l and 1 nmol/l respectively and were stable at these values for the remainder of the experiment. I supplementation eliminated the thyroid depletion of this element, caused serum T, concentration to rise and stabilize at 90 nmol/l by week 18, and T, concentration to stabilize at 2 nmol/l by week 6. From week 6 onwards, wool growth was increased 13% by I supplementation, whereas empty body growth was unaffected.5. Lambs grazing kale developed haemolytic anaemia, due to rumen fermentation of SMCO. I supplementation enabled the lambs to resist the anaemia better by increasing erythrocyte reduced gluthathione (GSH) content. Relative to pasture-fed animals, lambs grazing kale and supplemented with I showed increased heart muscle weight and cytochrome oxidase activity. This represented a compensatory mechanism for the reduced blood oxygen-carrying capacity caused by the anaemia. I-deficient (1.e. control) lambs grazing kale showed reduced cytochrome oxidase activity in both heart and hind-limb muscle.6. The findings are in accord with T3 having a greater biological potency than T4 for regulating rates of body and wool growth. Increases in heart weight, heart cytochrome oxidase content and erythrocyte GSH content of kale-fed lambs were, however, associated with elevation in serum T, and not T, concentration.7. I requirements of growing sheep and cattle consuming the pasture diets ar...

A study was undertaken to indicate the importance of different causes of death in goats and to investigate the management factors which influence these problems. Over a 15 month period, 324 dead goats were received from 67 farms in the Horowhenua, Wairarapa, Wanganui and Wellington regions. Although a wide range of diseases was encountered in the study, the major causes of mortality could be divided into 4 groups: problems directly related to management, microbial diseases, nematode parasitism, and trace element related deficiencies and toxicities. The highest proportion of deaths related directly to management problems and included deaths from hypothermia, mismothering, premature birth, ruminal acidosis, pregnancy toxaemia, trauma, and plant and chemical toxicities. In larger flocks, microbial diseases including Pasteurella pneumonia and yersiniosis were major problems. Deaths from nematode parasitism were predominantly observed in goats 12 months of age and older. White muscle disease (selenium/vitamin E deficiency) was the major trace element deficiency causing death in goats. The influence of factors including age of goat, flock size and management practices on the major causes of death are discussed.

Animals fed sole diets of kale (Brassica oleracea) were compared with animals fed ryegrass-clover pasture grown on the same soil type in two experiments. In Expt 1 young cattle grazed the two forages for 24 weeks, with supplementary copper and iodine being administered by injection. In Expt 2 young sheep were individually fed the two forages indoors at equal D.M. intake.Animals grazing kale in Expt 1 showed the characteristic symptoms of haemolytio anaemia from ruminal fermentation of S-methyl cysteine sulphoxide (SMCO) (Smith, 1974). This was most severe over the first 6 weeks, during which live-weight gains were very low (250 g/day). In the absence of copper supplementation animals grazing kale showed symptoms of copper deficiency. This was characterized by live-weight gain remaining low throughout the experiment (mean 280 g/day), rapid depletion of liver copper reserves, progressive reductions in serum copper concentration, reductions in erythrocyte copper and reduced glutathione (GSH) concentrations and a massive hepatic accumulation of iron. Copper deficiency only slightly lowered heart muscle copper concentration in kale-fed cattle, and this was counteracted by heart hypertrophy. The major effects of copper deficiency in kale-fed cattle were in erythrocytes, and a metabolic diagram is presented showing these effects to be biochemically similar to those produced by ruminal fermentation of SMCO.Copper supplementation of animals grazing kale increased live-weight gain (mean 425 g/day), reduced Heinz body formation, allowed the animals to recover gradually from the haemolytic anaemia and prevented other symptoms of copper deficiency. In contrast, animals grazing ryegrass-clover pasture showed only a very mild depletion of copper, there being no response in live-weight gain to copper supplementation.Activity of the enzyme glutathione peroxidase (GSH-Px) in whole blood was dependent upon blood selenium concentration in cattle fed both diets. In cattle fed on kale, bub not on pasture, reductions in erythrocyte GSH due to ruminal fermentation.. of SMCO and to copper deficiency were also associated with depressed blood selenium status.Glucosinolates were present in the kale (11 /*M/g D.M.) but absent from the pasture diet. Despite this, neither T 4 production from the thyroid gland nor the conversion of T 4 to T 3 appeared to be impaired by kale feeding in either Expt 1 or Expt 2. In Expt 1 serum T s concentration was better related to live-weight gain than was serum T 4 concentration, in accord with T 3 being the active form of the thyroid hormone.It is concluded that supplementation with copper but not iodine is essential where growing cattle are fed sole diets of kale for periods in excess of 12 weeks.

Reference curves demonstrating the relationship between serum or liver vitamin B12 and weight gain were derived from the examination of 16 published and 48 unpublished N.Z. trials. From these curves probability of obtaining an economic reponse (>10g/day body weight increase) for any serum or liver vitamin B12 can be determined. No significant (P<0.05) weight gain responses occurred to vitamin B12 or cobalt treatment in trials with mean serum vitamin B12 levels above 500 pmol/l or liver vitamin B12 levels greater than 500 nmol/kg. The reference curves were therefore derived from trials with vitamin B12 levels below these levels; 36 trials with serum vitamin B12 and 19 trials with liver vitamin B12 data. The mean vitamin B12 level at the mid point of the weight gain response period was selected from each trial. Examination of serum vitamin B12 reference curves for spring, summer, autumn and winter indicated that curves derived from data closest to the middle of January (summer) adequately reflected response to treatment at any time during the first year of life. Reference curves for liver vitamin B12 also used data closest to middle of January. This was partly because insufficient liver data was available to compare seasonal variations. The fitted response curve approached 0 gram/day at 500 pmol/l for serum vitamin B12 and 375 nmol/kg for liver vitamin B12. The minimum vitamin B12 level at which an economic response to treatment (>10 g/day) is not likely was 336 pmol/l for serum and 282 nmol/kg for liver.

Synthetic SMCO was added to basal diets of either fresh kale or lucerne at the concentrations 0, 0-2, 0-4, 0-8 and 1-6% D.M. and each diet offered ad libitum to groups of four lambs that were individually fed indoors. Within each group, two lambs were of haemoglobin genotype AA and two were AB. Initial live weight (W) was 21 kg and the experiment lasted for 6 weeks.SMCO supplementation depressed voluntary intake, body growth and wool growth, caused the development of haemolytic anaemia and produced kidney hypertrophy. Effects were much more severe when SMCO was added to a kale than to a lucerne diet, with the lowest SMCO intake of kale-fed lambs (0-3 g/kg W) producing marked detrimental effects whereas the highest SMCO intake of lucerne-fed lambs (0-7 g/kg W) produced only small and transient effects. The intake depressions were evident during the first week of SMCO supplementation and persisted throughout the full 6-week feeding period. Approximately 80 and 65% of the changes in body growth and wool growth could be accounted for by changes in intake, and it was concluded that the most important effect of SMCO in ruminant diets is as an intake depressant.It is suggested that the greater ratio of soluble to structural carbohydrate in kale (2-3) compared with lucerne (0-9) probably resulted in a microbial population developing in the rumen of kale-fed sheep that could metabolize SMCO to dimethyl disulphide at a faster rate than occurred in the rumen of lucerne-fed sheep. Dimethyl disulphide production is postulated as the cause of both the haemolytic anaemia and appetite depression. Plasma SMCO concentrations did not increase with increasing SMCO intake in sheep fed either diet, indicating that there must have been negligible absorption of this amino acid from tho digestive system.No haemoglobin C was produced by any of the lambs fed lucerne, and kale-fed lambs produced significant amounts only during weeks 5 and 6, with type AA lambs producing more than type AB lambs. However, there was no difference between AA and AB lambs in rate of decline in total haemoglobin concentration or upon voluntary intake, body growth and wool growth.