Weaner Sheep Research Articles

The utilization of nitrogen and sulfur by weaner and mature merino sheep

The intake, excretion, and retention of nitrogen and sulfur were measured in weaner (liveweight 15-17 kg) and mature (40-45 kg) Merino sheep offered ad libitum amounts of three pasture hays. The hays (H, M and L) varied in their content of digestible organic matter (71, 59 and 45%), of nitrogen (2.84, 0.72 and 1.20%), and of sulfur (0.20, 0.13 and 0.09%). When given the most-digestible hay (H), the weaners retained more nitrogen than did the mature sheep (0.97 v. 0.81 g per l00g digestible organic matter intake (DOMI), but there was no difference in retention of sulfur (79 v. 74 mg per l00g DOMI)). However, on the basis of metabolic liveweight, the weaners incorporated more of both nutrients into tissues, while the mature wethers incorporated more nitrogen and sulfur into wool. The retention of nitrogen and of sulfur per unit of DOMI were similar for each age group of sheep when the medium quality hay (M) was given. Mature sheep again incorporated more of each nutrient into wool. With the poorest quality hay (L), the weaners excreted more nitrogen and sulfur as a proportion of the amounts consumed than did the mature sheep. This resulted in a lower retention of nitrogen (-1.45 v. -0.74 g per l00g DOMI) and sulfur (-77 v. -14 mg per l00g DOMI) by the weaners. There was a lower incorporation of nitrogen into tissues per unit of metabolic liveweight by the weaners, and the mature sheep incorporated more nitrogen and sulfur into wool. The weaners grew wool less efficiently (g per l00g DOMI) than the adult sheep on all diets, the difference being greatest when the poorest quality hay was given. These results are discussed in relation to the nature of tissue energy reserves in weaner sheep.

The effects of anthelmintic treatment and season on the quantity and quality of wool grown by Merino sheep

Groups of 30 Merino weaner sheep were grazed in East Gippsland, Vic., and subjected to one of four anthelmintic programs during the 12-month period from December 1977. They were treated with thiabendazole either weekly (W), nine times (H), three times (L) or once (S). These programs resulted in marked differences in the degree of parasitism between the groups. Over the 12 months, parasites had no significant effect on yield, staple length or crimp frequency. However, compared with the wool from sheep treated weekly, greasy wool production was depressed by 13, 22 and 20% respectively in sheep given nine, three or one anthelmintic dose. Fibre diameter was also reduced. Dyebands were used to delineate wool grown during summer, autumn, winter and spring. Where parasite burdens were minimized (W group), wool growth, fibre diameter and rate of staple growth increased each season throughout the year. There was little increase in these characters in the other three groups until the spring, and wool growth and fibre diameter were significantly less than that of the W sheep in all but the initial summer season. Wool growth:fibre volume ratios indicated that sheep continued to initiate new fibres at least until the end of summer, when they were 9 months old. The subsequent depression in the wool growth of sheep dosed at less than weekly intervals provides further evidence of the deleterious effects parasites may have on the production of young sheep, even where anthelmintic is administered fairly frequently.

Supplements for Merino weaner sheep grazing mature pastures in summer and autumn

Two grazing experiments were conducted to study the short term effects (up to the following shearing in November) on Merino weaner sheep of supplementing senescent perennial ryegrass-subterranean clover pasture with oaten grain, lupin grain and soya bean meal from January to the beginning of April. In the first experiment, weaners grazed hay aftermath or mature uncut pasture. The supplements given daily were: none, oaten grain 0.28 kg/sheep, lupin grain 0.24 kg, soya bean meal 0.15 kg, soya 0.10 kg + lupin 0.08 kg, lupin 0.16 kg +soya 0.05 kg. The second experiment was designed to produce a response curve, relating the amount of lupin grain supplement (0-0.35 kg/sheep in 50 g increments) offered daily to weaners on hay aftermath, to their growth and wool production. A further group was given 0.25 kg oaten grain/sheep. In the first experiment, the difference between pastures was apparent in liveweight at the end of supplementation in early April (24-8-22.0 kg), liveweight in August (31 SO-29.2 kg), wool growth during supplementation (0.89 and 0.70 kg) and greasy fleece weights (4.2 and 3.8 kg) (hay aftermath and uncut pasture respectively). Supplemented groups were 2-3 kg heavier than unsupplemented ones but differences between groups given different supplements were not significant except those between lupin and oat fed weaners on hay aftermath at the end of supplementation. Fleece weights were not significantly affected by the type of supplementation but animals on predominantly soya bean meal supplements had higher greasy fleece weights than the controls. Liveweights at the end of supplementation in experiment 2 did not respond to increased amounts of lupin grain above 0.2 kg and there was no significant response in wool growth to increments of lupin grain. Liveweights at shearing were significantly different only in groups offered the largest (0.35 kg) and the smallest (0.05 kg) amounts of lupin grain. Sheep in the control group were lighter than all others except those given the smallest amount of lupin grain. The only significant difference in greasy fleece weights (0.7 kg) was between those from control sheep and sheep given the highest level of supplementation. In both experiments there was evidence of substitution of oaten grain for pasture, but this did not significantly reduce liveweights or fleece weights relative to those of sheep in groups receiving the same amount of energy in lupin grain. Final liveweights were influenced as much by liveweights at the start of the experiments as by the type or amount of supplement offered to the weaners in summer.

Population dynamics of the parasitic stages of Ostertagia spp. in sheep

Callinan A. P. L. and Arundel J. H. 1982. Population dynamics of the parasitic stages of Ostertagia spp. in sheep. International Journal for Parasitology 12: 531–535. The development and survival of continuing infections of Ostertagia spp. in weaner sheep were studied in order to develop a general model of the parasitic stages of the life cycle of these sheep nematodes. After 10 days, 13.8% of infective larvae (L 3) given at the rate of 1 dose of 1000 L 3 twice per week (group 1) and 20.8% of L 3 given at the rate of 10,000 L 3 twice per week (group 2) were recovered in the first of the serial nematode counts. In the final counts at 137 days, 7.7 and 0.7% were recovered in these groups. The build up and maintenance of nematode populations was regulated and related to the level of infection. A model in which the death rate of the parasitic stages was a function of the time of exposure to infection and rate of infection was used to describe the serial total nematode counts. During the experiment there was no noticeable trend in numbers of fourth stage larvae (L 4) in nematode counts, the size of adult nematodes, nematode egg counts (EPG) and egg output per female nematode (EPF). After 112 days, liveweight gains were significantly reduced in group 2 only, but increases in wool lengths were significantly reduced in both groups.

A model of the life cycle of sheep nematodes and the epidemiology of nematodiasis in sheep

A computer model (NEMAT) of the life cycle of sheep nematodes and of the epidemiology of nematodiasis in sheep was constructed. Its purpose is to predict the development of nematodiasis in weaner sheep and to determine optimum nematode control programmes. It has been developed for use in western Victoria, Australia, but it should also be of use in other localities. NEMAT simulates the growth of perennial ryegrass ( Lolium perenne) and subterranean clover ( Trifolium subterraneum) pasture and weaner sheep and the development of populations of the sheep nematodes Ostertagia spp. and Trichostrongylus spp. The development and death rate parameters of the free-living stages of these nematodes were estimated by a direct search optimisation procedure specifically developed for this study. The death rates of the parasitic stages of Ostertagia spp. were determined in a field experiment and expressed as a function of the rate of infection and the time of exposure to infection. Other probability density functions and deterministic functions needed to complete the quantification of the sheep-nematode system were derived from published reports or personal communications. NEMAT was validated against data from two independent field experiments carried out in western Victoria. Predicted serial measurements of pasture availability, liveweights, total nematode counts, nematode eggs per gram of faeces and numbers of infective nematode larvae per hectare were compared with those actually observed. The predicted and observed measurements were subjectively similar and could not be differentiated statistically by spectral analysis. NEMAT was then used to evaluate some nematode control programmes in western Victoria. Using observed weather data, it simulated the continuous development of nematode populations during 1957–1976 on pastures set stocked on the 1st of January each year with recently drenched weaner sheep. If sheep were drenched in only one month of the year, the effect of this drench on liveweights and woolweights at the end of the year was greatest if it was given in February. There was a progressive decline in final liveweights and woolweights if it was given in subsequent months to December. If sheep were drenched in February and given a second drench in any one of the remaining months of the year, the effects of this second drench on final liveweights and woolweights was greatest if it was given at the autumn break. A drench in February and a drench and shift to ‘clean’ pasture (<10 4 nematode larvae per hectare) in July were always sufficient to limit the mean yearly effects of nematodiasis to 1 kg in liveweight and 0·1 kg in woolweight. When such a shift was not possible, a drench in February, another at the autumn break and 0–5 drenches in winter and spring were required to attain similar productivity. The number and timing of these drenches after the autumn break depended on the daily effects of weather on the nematode population and could be determined only by a model of the sheep-nematode system such as NEMAT.

Effects of a preventive and suppressive control scheme on the development of thiabendazole-resistance in Ostertagia spp.

Three years after the start of an experiment to assess the merits of thiabendazole (TBZ) treatment of trichostrongylid parasites in weaner sheep, field isolates of Ostertagia spp and Trichostrongylus spp were made from weaner sheep treated under one of three treatment schemes. Treatment frequencies were "nil", "planned" (5 or 6/year) and "regular" (every 3 weeks). In addition an isolate was taken from a group of "tracer" sheep drenched with TBZ every 10 days. Resistance to TBZ was assessed using an in vitro egg hatch assay, pre- and post-treatment faecal egg counts and a controlled anthelmintic efficiency test. Pre- and post-treatment egg counts revealed the presence of TBZ-resistance in field isolates of mixed species. Egg hatch assays indicated a level of resistance for Ostertagia spp which was proportional to the frequency of TBZ treatment. The "planned", "regular" and "tracer" strains of Ostertagia spp had resistance ratios for eggs of 4, 13 and 15 respectively when compared to the "nil" strain. In the anthelmintic efficiency assay treatment with 44 mg kg-1 and 88 mg kg-1 of TBZ removed 82 and 96% respectively of the total Ostertagia burden (adults and larvae) from the "nil" strain and 30 and 75% respectively from the "planned" strain. The same dose rates against the "regular" and "tracer" strains and additional rates of 132 or 176 mg kg-1 against the "tracer" strain failed to reduce the Ostertagia burden significantly. Intestinal Trichostrongylus spp from all isolates were fully susceptible to TBZ at 44 mg kg-1. Levamisole at 7.0 mg kg-1 was highly effective (99% reduction) against the "tracer" strain of Ostertagia.

Oxidized copper wire particles for copper therapy in sheep

Ninety Merino weaner sheep were assigned to one of six groups on the basis of liveweight and liver copper concentrations. Sheep in four groups each received one oral dose of oxidized copper wire particles, viz. 2.5, 5, 10 or 20 g per animal. Sheep in another group each received a subcutaneous injection of 12 mg copper as diethylamino cupro-oxyquinoline sulfonate and another group of sheep did not receive any copper supplement. Liver copper concentrations responded positively to copper oxide load. The 2.5 g dose of copper oxide wire was more efficacious than the commercial injectable product in raising copper status, but the higher doses of oxide raised liver copper concentrations to values similar to those recorded in cases of copper poisoning. Copper concentrations in blood plasma, muscle and kidney were not altered by the copper load. No clinical signs, nor biochemical or histological evidence of acute copper toxicity, were found. Liver copper values fell in all sheep from 10 weeks after copper therapy until the end of the trial at 50 weeks post-therapy. Over this period of 40 weeks, the rate of mobilization of liver copper was linear and was positively related to the initial concentration of copper in the liver. A significant proportion of the oxidized copper wire dosed to sheep was recovered in the forestomachs and abomasa of selected sheep 4 weeks after dosing. No evidence of abomasal damage due to particles could be established. It is concluded that oral dosing of oxidized copper wire is a safe and effective method of copper supplementation to sheep.

Intake of selenium and other nutrients in relation to selenium status and productivity of grazing sheep

The selenium status of the sheep and seasonal fluctuations in the intake of dry matter, digestible dry matter and selenium over a 12-month period were measured in an experiment with 80 ewes and their offspring on annual pasture in the south-west of Western Australia. Forty of the ewes received an intraruminal selenium pellet 1 month prior to lambing in June. At weaning half of the lambs born to ewes in each treatment also received an intraruminal selenium pellet. There was a distinct seasonal pattern in the quality and quantity of pasture ingested. Dry matter digestibility was highest in winter (68.9%), declined during spring and was lowest during summer (32.3 %) when intake of digestible dry matter was not sufficient to maintain the liveweight of weaner sheep. Selenium intake by ewes was highest in winter (64 �g/day), when dry matter (DM) intake was maximum (1348 g/day). The intake of selenium (31 �g/day) and the plasma selenium concentration (7.8 �g/l) of unsupplemented ewes was least in spring when pasture was actively growing and its selenium concentration was declining. Plasma and liver selenium concentrations were least at weaning, both in lambs from unsupplemented ewes (3 �g/l and 0.093 mg/kg DM respectively) and from supplemented ewes (7 �g/l and 0.120 mg/kg DM respectively). Selenium supplementation of ewes resulted in elevated selenium concentrations in the plasma of their lambs up to 8 weeks of age. Plasma concentrations declined thereafter and by weaning, at c. 18 weeks, there was little difference between plasma selenium concentrations of lambs from supplemented and unsupplemented ewes. Despite a low selenium status of unsupplemented weaners, supplementation did not improve growth rate during the summer and autumn, the period when problems of selenium inadequacy have been recorded previously.

The effects of nematodiasis on weaner sheep in Western Victoria

The development of nematodiasis and its subsequent effect upon production from Merino weaner sheep in western Victoria was studied at Hamilton during 1975-77. In each year, all weaners were drenched in summer and allocated to groups of 36, stocked at 15 sheep ha-1. The groups were given oral anthelmintics weekly, monthly or on five, two or one occasions between March and December of each year. A further two groups were not drenched, but one of these groups was given access to anthelmintic blocks. Nematodiasis was prevalent from the commencement of continuous pasture growth in autumn until early summer. Its effect varied considerably between both years and treatments. Undrenched sheep gained 39-66% less liveweight and grew 16-30% less wool than sheep drenched weekly. In two of the three years, liveweight gain and greasy fleece weight increased with frequency of anthelmintic treatment. The mean faecal egg count (EPG) in untreated sheep during the three years was over 500 eggs g-1 dry faeces and the mean number of nematode larvae ha-1 (LPH) was c. 1 x l06. Only those groups of sheep receiving 5, 12 or weekly drenches during the experimental periods had EPG or LPH that were significantly less than those of the undrenched sheep. Two to five anthelmintic treatments between March and December gave adequate control of nematodiasis.

Gastro-intestinal parasites in sheep in an arid environment

Internal parasitism and its effects on survival, wool growth and liveweight gain of weaner sheep were studied over 3 years from 1977 to 1979 at Fowlers Gap Research Station, Broken Hill, New South Wales. During this period, annual rainfall was 33, 152 and 141 % respectively, of the annual mean of 195 mm. Worm burdens and production of sheep given anthelmintic treatment at approximately monthly intervals were compared with those in untreated sheep. Total worm counts in untreated sheep were low, ranging from 1 5 to 3750. Nematodirus spp. were the most common nematode parasites recovered. lnfections with Trichostrongylus spp, were recorded in 2 of the 3 years; T. rugatus was the only species represented when species identification was made in 1979. Infections of Haemonchus contortus were only detected in the last year. Tapeworms (Moniezia spp.) were occasionally recovered. Anthelmintic treatment reduced worm burdens to a very low level but had no significant effect on survival rate, liveweight gain, or wool production. We concluded that in the arid areas of western New South Wales, worm infection would not limit production or cause mortality in young sheep, except in unusually wet years.

Effect of vitamin B12b injections on the growth of young Merino sheep

In two experiments near Robe in the south-east of South Australia, on soil highly prone to the occurrence of cobalt deficiency in sheep, the effect of injections of vitamin B12b (hydroxocobalamin) on grossly cobalt-deficient weaner sheep and suckling lambs was compared with the effect of oral doses of cobalt as liquid drenches or ruminal pellets. All the supplements used were effective in treating cobalt-deficient weaned sheep or preventing the onset of cobalt deficiency in lambs. A single injection of vitamin B12b (1 mg), under the conditions of these experiments, satisfied the requirements of lambs for 14 weeks and cobalt-deficient weaner sheep for up to 40 weeks. The use of vitamin B12b in preventing or correcting cobalt deficiency in sheep in the field is discussed. Serum vitamin B12b concentration was not a reliable indicator of the vitamin B12b status of young sheep which had been given single injections of vitamin B12b. Vitamin B12b, deficiency in sheep was associated withdecreased concentrations of blood haemoglobin and of glucose, total proteins, urea and cholesterol in blood serum. The activities of serum aspartate transminase and alkaline phosphatase did not appear to be affected by the vitamin B12b status of the sheep.

The influence of dietary protein and energy concentration on the growth of Merino weaner sheep

The influence of the dietary concentration of protein and energy on the growth of Merino wether weaners in pens, was studied in a factorial experiment. There were two digestible energy concentrations, (12.4 and 14.2 MJ DE kg-1 DM) x five protein concentrations (9-21% CP), three replicates (each of one animal). Diets were offered ad libitum, and nitrogen and energy retention were determined by the comparative slaughter technique. Initially, the mean weight of all treatment groups was 15.5 kg liveweight (12 weeks of age), and the experiment concluded 14 weeks later. Daily dry matter intake, liveweight gain, wool growth and total body nitrogen retention increased linearly as dietary crude protein concentration increased. Higher energy concentrations reduced dry matter intake and liveweight gain, and increased wool growth. Approximately 21 % of the digestible energy intake was retained. Regressions relating carcase and non-carcase composition to compartment weight, are presented. The fastest and most efficient gain in liveweight occurred with the ration containing 20% CP, at the lower energy concentration. It is suggested that for high levels of production with Merino weaners, rations should contain at least 18% CP.

The effect of residual grain on the utilization of sweet lupin stubbles and concurrent changes associated with lupinosis, in particular changes in liver copper and zinc in weaner sheep

An experiment was conducted with Merino wether weaners to examine the influence of lupin grain on the utilization of stubbles from crops of sweet, narrow-leafed lupins (Lupinus angustifolius cv. Unicrop). Sheep grazed at 25 ha-1 without additional grain or with grain (350 kg ha-1) added to the stubble gained weight over 65 days, but those with the additional grain grew faster (av. 126 v. 77 g d-1). At 50 ha-1, sheep grazed on normal stubble gained weight for only 44 days at a mean rate of 82 g d-1, while those with the additional grain (350 kg ha-1) reached a peak weight after 65 days of little growth (31 g d-1). The sheep developed lupinosis. Those grazed at 50 ha-1 suffered more liver damage than those at 25 ha-1, and liver copper levels increased while zinc levels decreased as the severity of liver damage increased. Plasma ornithine carbamyl transferase (OCT) was of minimal value in the diagnosis of lupinosis.The levels of plasma glucose were generally higher in the sheep grazed at the low stocking rate.

Parasitism and production in weaner sheep grazing alternately with cattle

Three systems for the post-weaning management of Merino wethers were compared over two years. In all systems, the sheep were given two anthelmintic treatments with levamisole per year; at weaning in January, and in July. In the first system (SC) the same paddock was used as a weaning paddock each year in succession. In the second system (SC 6) sheep and cattle grazed the paddock alternately for 6- month periods from January and July; the third system (SC 12) comprised sheep and cattle grazing alternately for 12-month periods from July of each year. Compared with the SC treatment, weaners from the SC 6 treatment had significantly lower faecal egg counts and lower burdens of Haemonchus contortus, Trichostrongylm axei, Trichostrongylus colubriformis and Nematodirus spp. They had significantly higher numbers of Cooperia oncophora and similar numbers of Ostertagia circumcincta. SC 6 sheep made greater liveweight gains, produced heavier fleeces, and suffered lower mortalities than their SC counterparts. Results for the SC 12 system were usually intermediate. In a third year, the SC 12 system was modified to include a monthly treatment with levamisole. The liveweight gains, egg counts and mortalities of the monthly treatment sheep did not differ significantly from those of the SC 6 sheep. Both systems were superior to the SC treatment in controlling nematode infections in weaner sheep. There were no significant effects of any treatment on liveweight gains of cattle, although outbreaks of ostertagiosis occurred in the third year in two of the four replicates of the SC system.

White muscle disease of sheep and associated tissue selenium levels in Western Australia.

White Muscle Disease of sheep occurs in Western Australia as distinct syndromes in lambs and weaner sheep. Mean liver selenium concentrations of lambs and weaners with WMD and unaffected by WMD were 0.19 and 0.46 ppm, and 0.20 and 0.41 ppm (dry weight) respectively. There was considerable overlap between levels suggesting that selenium status was not the only factor involved in the development of WMD.

The comparative nutritive value for weaner sheep of stubble and grain of pea, vetch and lupin crops

Weaner Merino wethers were used in three experiments to compare the nutritive value of lupin, pea and vetch grains and stubbles. In the first experiment, grain was offered either as the sole ration at 250 g day-1 or as a supplement of 0, 250 or 750 g day-1 to wheat chaff which was offered ad libitum. The grains were pea, vetch, lupin, barley and a 311 mixture of barley and lupin. The mixed grain was not offered as the sole ration, nor was barley offered as a supplement at more than 250 g day-1. There were only small differences in the nutritive value of the grains. The sheep ate less chaff when offered lupin or barley plus lupin grain than when offered pea or vetch grain. However, because the digestibility of the diets was higher with lupins, digestible organic matter intakes were similar within a level of feeding for the three legume grains. Substitution of barley for 75% of the lupins resulted in a lower intake of digestible organic matter than occurred with 100% lupins. In the second and third experiments the three legume grains were offered at 160 and 500 g day-1 respectively, in combinations with chaff of lupin, pea or vetch stubble offered ad libitum. Some differences in the value of the chaffs were found, but the grains had similar nutritive values when offered with any particular chaff. There were significant linear regressions between digestible organic matter intakes and liveweight gain, which were similar for the three experiments, with no differences between type of grain or type of chaff.

In vivo prediction with tritiated water of chemical and dissectible components of the dressed carcass of sheep growing at different rates

Two groups of Border Leicester x Merino wether weaner sheep were given a concentrate ration either ad libitum or at 60% ad libitum. Mean growth rates were 255 and 136 g/day respectively. Animals were slaughtered at predetermined liveweights over the range 20–45 kg after a 30 hr fast, during which tritiated water (TOH) space was measured. The right half-carcass was dissected into fat, muscle and bone, and the left half-carcass was minced and analysed for chemical components (fat, protein, ash, water and energy). The relationships between the weight of carcass components and carcass weight were examined by regression analysis and were similar for both groups. Relationships between the weight of dissected fat, muscle and bone and chemical fat, protein and ash respectively were also determined. The chemical and dissected composition of the carcass could be predicted accurately from fleecefree fasted liveweight. The addition of TOH space to the regression equation improved the prediction of dissected and chemical fat and energy. The most accurate equation for bone included liveweight and age. It is suggested that tritiated water has only limited application in the prediction of dressed carcass composition in vivo.

Effects of formaldehyde treatment of high quality pasture hay on its utilization by weaner sheep

Pasture hay of 18 per cent crude protein content was chaffed and sprayed with an 8 per cent solution of formaldehyde in a concrete mixer. This, or similar untreated chaffed hay was fed to Merino weaner sheep in four experiments as follows: 1. Twenty-four sheep grazing in a 0.9 ha paddock were penned individually three times a week and fed 700 g of either treated or untreated hay. During the intervening periods they were released and allowed to graze. 2. Twelve sheep penned indoors were given 300 g day-l of either treated or untreated hay as a supplement to a basal diet of hay which contained nine per cent crude protein. 3. Twelve sheep penned indoors were fed either treated or untreated hay ad libitum. 4. Six sheep in metabolism cages were fed either treated or untreated hay at a daily rate of 52 g kg-I liveweight0.75 A crossover experimental design was used. Wool production, body growth and, in experiment 4,nitrogen balance were recorded. Attempts were also made to gauge the effectiveness of the treatments in protecting the protein from ruminal degradation. Although the level of protection obtained compared favourably with that obtained by other workers with forages, significant differences in animal production were shown only in experiment 2, where the basal hay was utilized less efficiently for body growth when the supplement was treated, in experiment 3. where treated hay was utilized less efficiently for body growth, and in experiment 4, where wool growth was increased by 10 per cent and nitrogen retention was also increased by treatment of the hay. It was concluded that the magnitude of any likely beneficial response to treatment is too small to warrant this treatment of hay being undertaken on a large scale.

Comparison of lupin varieties for nutritive value as dry standing feed for weaner sheep and for incidence of lupinosis

Several lupin varieties were grown on sandy and sandy gravelly soils in a Mediterranean environment. During the three years when they were grown, the rainfall varied from 400 to 700 mm. The yields of dry matter and grain for the cultivars Borre, New Zealand Blue, Uniwhite and Uniharvest of L. angustifolius were not significantly higher than those of the Chapman cultivar of L. cosentinii and the Weiko III cultivar of L. luteus. However, more blocks of these last two cultivars failed owing to weed competition. The nitrogen, phosphorus, sulphur, sodium, neutral detergent fibre and water-soluble carbohydrate contents of the stem, leaf, pod and seed at maturity did not differ greatly between varieties within years. Weaner Merino shcep grazed at 50 sheep ha-1 on these standing dry crops gained up to 10 kg in 80 days. Sheep weight gains over three years were consistently the best for sheep on Borre, Uniwhite and Uniharvest; sheep on Chapman lupins gained little weight in any year, whilst Weiko III gave intermediate gains in one year and poor gains in another. The differences in weight gain were associated in all years with differences in the initial amounts of grain present. Detailed nutritional studies on sheep in the first year showed that the nutritive values of the varieties not causing lupinosis were similar in terms of digestible organic matter intake, volatile fatty acid production and proportions, and blood urea concentration. Abnormal liver metabolism, inferred from the level of ornithine carbamoyl transferase in the blood, occurred in sheep on all varieties during the three years, and lupinosis was confirmed by necropsy in two of the years. Lupinosis resulted in nine deaths out of 250 sheep, but other sheep with liver damage achieved normal liveweight performance. In each year, liver damage occurred on dry lupins before any summer rain. There was a high incidence of lesions of the fungus Phomopsis rossiana on stems of the cultivars Chapman and Weiko III during growth. The presence of lesions at this stage appeared to be more closely associated with the occurrence of lupinosis in summer than with the incidence of Phomopsis infection on dry sterns following summer rains.

Lupin crops in pastoral systems for weaner sheep in a mediterranean environment

The use of dry standing crops in summer in pastoral systems for weaner sheep was evaluated in three experiments. In the first experiment, production was studied for 2 years on farmlets stocked with Merino ewe weaners at 7.5 and 12.5/ha. Summer growth rate of sheep on farmlets having 20% of their area sown to lupins ( L. angustifolius cv. Borre) was better than on farmlets with vetches ( V. sativa cv. Nyabing) or pasture only; sheep on farmlets with oats (cv. Avon) lost weight. Over the whole year wool production and final liveweights were similar on all systems, but those with lupins and vetches required less hand feeding. In the second experiment farmlets with either pasture only or with pasture and lupins were stocked with similar sheep at 7.5 and 10.0/ha and compared over 3 years. Drought affected either lupin or pasture growth in the first 2 years. In the third year at the stocking rate of 7.5 sheep/ha sheep on farmlets having 20% lupins grazed for 20% or 30% of the year produced more wool in summer and over the whole year than sheep on pasture alone. At 10.0 sheep/ha more wool was produced in summer, but not over the whole year. Systems where heavier utilisation of the lupins was practised were inferior to systems with only pasture. In a third experiment the best time to feed lupins was examined. The greatest benefit in wool production occurred when lupins were utilised in late summer. However, the largest weight gains occurred when lupins were used in early summer. The experiments substantiated earlier work on the high feed value of lupins in summer in Mediterranean environments. Their value in sustaining high stocking rates with lower amounts of supplementary feed is due to the high yield. Yields of 9,000 kg/ha dry matter were obtained on soils that produce only 3–4,000 kg/ha dry matter of pasture. Grain yield accounted for 20% of total yield. The grain was variable in quality, ranging over the years from 5.0 to 5.6% nitrogen and 27 to 49% neutral detergent fibre. The potential deaths from lupinosis must be offset against the increased animal production. Further work is needed on the disease.