Born Lambs Research Articles

The management and performance of a flock lambed in May

By lambing upland ewes in May, it is possible to match the ewe's nutritional needs closely with grass growth (Newton et al 1982). Requirements for high cost housing and supplementary feeding during late pregnancy can be minimised. The resulting late born lambs should be available for sale as ‘out of season’ lamb when prices are at their highest. Delayed tupping, however, has been shown to reduce lambing performance in most breeds due to a lower ovulation rate (Land et al 1969). Ewe fertility, by contrast, is not affected as oestrus is strong with most indigenous breeds until February (Wheeler et al 1977). This experiment was designed to study the long term management requirements and performance of a late lambed (1 May to 5 June) flock and the efficacy of androstenedione (Fecundin) as a means of improving ovulation rate.

EWE PERFORMANCE AND LAMB LIVEWEIGHT GAINS COMPARED FOLLOWING AUTUMN AND SPRING LAMBING

A flock of 370 Dorset x Romney ewes with up to 96% autumn lambtng was developed without the aid of hormones. Data from flock and experimental records were used to compare the performance of autumn- and spring-born lambs and their dams. Preliminary findings for three seasons show that ewes lambed in autumn had a greater spread of lambing, lower litter size and fewer perinatal lamb deaths. Growth of suckling lambs was similar in winter and spring. After weaning, autumn-born lambs grew faster than spring~born lambs of the same age (104 v 34 g/hd/day). The proportion of lambs reaching killable weights by January was 90% and 10% for autumn and spring lambs respectively. Keywords: Lambing time, autumn, spring, lambing performance, lamb liveweight gain.

Cryptosporidium spp. in new born lambs in Iran.

In a study conducted to investigate the causes of the death of new born lambs due to diarrhoea 237 cases were studied. In 16 of these lambs necropsied at four to 10 days old organisms considered to be Cryptosporidia at various stages of its life-cycle were associated with the luminal surface of the epithelium of the intestinal tract. The histopathology and the mechanism of the diarrhoea caused by the parasite and the resulting deaths are discussed.

Thrombus formation on catheters in new born lambs.

Catheters were inserted into the aorta and inferior vena cava of newborn lambs by cutdown on the femoral vessels and directly into the umbilical vein. The lambs were killed after six days and the amounts of thrombus surrounding the cathethers were measured. Most catheters inserted into the umbilical vein looped within the liver and only a few passed directly into the portal vein or through the ductus venosus into the vena cava. On different types of catheters inserted via the femoral artery or femoral vein, there were significant differences both in the proportion with thrombus and the amount of thrombus. There were also significant differences in renal infarctions caused by different types of catheters.

A comparison of the performance of single and twin born Corriedale ewes and lambs

Reproductive performance of Corriedale sheep from the experimental farm at Mount Derrimut, Victoria, was studied over five years (1 968 to 1972) in a flock selected for the production of medium wool and the ability to produce twins. Traits measured included fertility at mating, lambing rate, twinning rate, mortality at birth and interval between mating and lambing. Ewes born as twins were less fertile at first mating, improved rapidly in their reproductive performance at subsequent matings, but then declined in fertility quite early in their breeding life. Twin lambs had a mortality rate at birth nearly three times that of singles, were lighter at birth, grew slowly up to weaning and produced less wool at weaning. Female lambs conceived as co-twins with male lambs tended to be disadvantaged in heir pre-natal development which could be due to an enhancement effect exhibited by the male co-twin.

Efficiency of growth and wool production of young Merino ewes from a flock selected for fertility

A handfeeding experiment was conducted with weaner ewe lambs from two Merino flocks. One flock had been selected for high net reproductive rate, growth rate and wool production (fertility flock) ; the other flock was a randomly selected control flock (random flock). Single and twin born lambs from each flock were used in the experiment. Lambs were randomized into four treatment groups and offered the diet either ad libitum or at one of three levels estimated to restrict growth rate to 50, 100 and 150 g day-1. At each level of feeding, fertility flock lambs grew faster and were more efficient in converting feed to liveweight gain. Over the whole experiment the feed conversion efficiencies in g gain per kg digestible organic matter intake per day were 218 and 185 (P < 0.05) for the fertility and random flocks respectively. There were no significant differences in growth rate or efficiency of conversion of feed to liveweight gain between single-born and twin-born lambs. Random flock lambs had a significantly higher wool growth rate and were more efficient converters of feed to wool than fertility flock lambs. Gross efficiencies were 10.8 and 9.1 g clean wool per kg digestible organic matter intake per day (P < 0.05) for random and fertility flock lambs respectively. Single-born lambs grew significantly more wool than twin-born lambs but there was no significant difference between birth types in the efficiency of conversion of feed to wool.

THE INCIDENCE OF DYSTOCIA IN FINE‐WOOL MERINO EWES

The mean incidence of dystocia in 1,510 fine-wool Merino ewes over a ten-year period was 4.1% of ewes lambing. In the 10 year period, 10% of all neonatal mortality was attributed to dystocia and in only 23% of dystocias was lamb presentation abnormal. The incidence of dystocia was not related to age of ewe. Significantly more ewes experienced dystocia at spring than winter (P less than 0.05) or summer (P less than 0.01) lambings. The mean birth weights of dystocic single and twin born lambs were 4.19 and 3.38 kg respectively. The corresponding birth weights of lambs that did not experience dystocia were 3.69 and 3.00 kg. More ewes experienced dystocia when stocked at 12 or 16 per ha than at 8 per ha (P less than 0.05). Fifty per cent of recorded dystocias occurred in ewes stocked at 16 per ha, 40 per cent at 12 per ha and 10 per cent at 8 per ha. Ewe body weight pre-lambing was not related to the incidence of dystocia but it would appear that weaker ewes are more likely to have a difficult birth than ewes that are stronger and in better condition.

In vivo and in vitro ethanolic fermentation of milk replacers by the naturally occurring yeast Torulopsis glabrata

SUMMARYAn investigation was undertaken to determine whether commercial milk replacers provide fermentable substrates for the yeast Torulopsis glabrata and thus produce ethanol in the stomachs of new born lambs and calves. Samples of stomach contents from calves in two small rearing units and a small number of farm bred calves, all being fed commercial milk replacers, were also examined. Ethanol was produced from certain replacers in all cases, and its association with Torulopsis glabrata was confirmed.

Attainment of puberty and reproductive performance in Clun Forest ewe lambs

SUMMARYCertain aspects of puberal development and reproductive performance in Clun Forest ewe lambs with a wide range of birth dates were investigated during the two seasons 1969–71. Of 33 ewe lambs born in the spring of 1969, 26 exhibited their first oestrus at a mean date of 8 November 1969 ± 2·5 days, the mean age being 228·3 ± 2·4 days and the mean body weight 36·3 ± 0·9 kg. The lambs which failed to breed in their first year, together with lambs born in the autumn of 1969, attained puberty during the autumn of 1970. Twenty-three ewe lambs carried foetuses to term in the spring of 1970 and had a mean lambing rate of 113·0 ± 7%. Of 84 ewe lambs born in the spring of 1970, 73 attained puberty in the first year of life at a mean date of 11 November 1970 ± 2·7 days, the mean age being 223·7 ± 3·0 days and the mean body weight 32·2 ± 0·5 kg. Cyclic activity of ewe lambs born in 1970 was recorded throughout their first breeding season. They experienced their last oestrus of the season at a mean date of 24 January 1971 ± 2·2 days, the mean age being 296·9 ±3·9 days and the mean body weight 32·4 ± 0·6 kg. The mid-breeding season was 18 December 1970, coinciding with the shortest days, and the mean number of heats exhibited throughout the season was 5·15 ± 0·24 per lamb.Marked individual variation existed in age and body weight at puberty and in breeding activity, largely due to differences in date of birth and growth rate during rearing. Ewe lambs born early tended to experience their first oestrus earlier in the season than late born lambs but they did so at a higher age and heavier body weight. Fast growth rate and earliness of puberty were associated with extended duration and enhanced regularity of cyclic activity. Time of birth was clearly of fundamental importance in relation to the onset and duration of breeding activity in the ewe lambs included in the present study.Adult rams of three breeds were found to vary consistently in the proportion of ewe lambs which they detected in oestrus, rams of the lambs' own breed being most efficient.

Free fatty acids and glucose in the plasma of newly born lambs: effects of environmental temperature.

Free fatty acids and glucose in the plasma of newly born lambs: effects of environmental temperature.