Mechanisms by which nutritional supplementation might improve colostrum production and enhance lamb survival were examined in adult Border LeicesterxMerino ewes. Ewes were either unsupplemented or supplemented with 500 g/day of oat grain, lupin grain or a formaldehyde-protected sunflowerseed meal (SFM) from day 130 of gestation until parturition while grazing spring pastures containing about 1000 kg green DM/ha. Blood samples were obtained on day 140, day 145 and immediately after parturition. Colostrum production at parturition and for the next 6 h was determined. A new method to determine concentrations of insulin-like growth factor-1 (IGF-1) is presented. Colostrum production at parturition (P.< 0.01) and IGF-1 concentration on day 140 (P.< 0.01) and at parturition (P.< 0.001) were higher, and progesterone concentrations on days 140, 145 and at parturition were lower (P.< 0.001) for single than twin bearing ewes. The unsupplemented ewes and ewes fed oat grain, lupin grain or SFM had an average weight of colostrum at parturition of 292, 328, 452 and 392 g (P.< 0.01), milk secretion rate to 6 h after parturition of 58, 64, 85 and l00g DM/h (P.< 0.05), IGF-1 concentrations after parturition of 199, 223, 262 and 265 ng/mL (P.< 0.001) and progesterone concentrations on day 140 of 49, 43, 39 and 41 nmol/L (P.< 0.01) respectively. Twin compared to single bearing ewes had about half the amount of colostrum at parturition per kg of lamb birthweight. Progesterone concentrations on day 140 and at parturition (P.< 0.01) were negatively related to estimated pasture intake during pregnancy, which was 17% higher for single than twin bearing ewes (P.< 0.05). Supplementation with lupins and SFM may be expected in similar circumstances to enhance the survival of multiple born lambs, while oat grain would not.
The meat quality of cross-bred cryptorchid lambs (6 months old) that had been grazed on chicory (Cichorium intybus; n = 20) or lucerne (Medicago sativa; n = 20) for 8 weeks preslaughter was studied. Unfasted preslaughter liveweight (range 42.5-51.5 kg) was not affected (P>0.05) by treatment. There was no difference (P>0.05) between groups for age at slaughter, hot carcass weight, or measures of fatness GR and Fat C (fat depth over longissimus thoracis et lumborum) when adjusted to a common carcass weight of 21.9 kg. Lucerne-fed lambs were, however, significantly (P<0.05) fatter at the 5th rib. There was no significant (P>0.05) difference between groups for pH, colour values (where L* indicates relative lightness, a* relative redness, b* relative yellowness), Warner-Bratzler shear values, or cooking loss. There was no significant (P>0.05) difference between groups for mean fat colour score or for the distribution of the scores. The b* values for subcutaneous fat tended (P = 0.06) to be greater for lucerne-fed lambs. A comparison of the mean values for aroma and flavour of the longissimus thoracis et lumborum showed no significant (P>0.05) difference between groups and no difference in overall acceptability. Finishing lambs on the chicory cultivar used in this experiment did not adversely affect meat quality and did not result in fatter carcasses than lucerne-fed lambs.
The effect of moderate undernutrition in mid pregnancy on lamb birth weight and survival of single- and multiple-bearing ewes is reported. A total of 1220 ewes of 3 crossbred types with different fecundity, Booroola Merino x Dorset (BD), Trangie Fertility Merino x Dorset (TD) and Border Leicester x Merino (BLM), were examined over 2 years. The treatments were low (L) and high (H) nutrition at pasture for 4 weeks from about day 75 of pregnancy. Ewe liveweight of the L group at the end of the treatments was 5 kg lower in 1984 and 8 kg lower in 1985 (P<0.01) than the H group. The differences were smaller by late pregnancy and post-lambing. The L treatment increased (P<0.01) birth weight by 0.16 kg in 1984 but had little effect in 1985. Litter size had the greatest effect on birth weight (P<0.01). Ewe crossbred type and lamb sex effects were also significant (P<0.01), although they tended to be reduced for higher order births. Nutritional treatment had no effect on gestation length. Ewe liveweight at joining and weight gains before and after the treatment period significantly affected birth weight and accounted for the large difference in birth weight between years (0.7 kg). Ewe weight gain during the treatment period in mid pregnancy had no significant effect on lamb birth weight. Nutritional treatment in mid pregnancy had no effect on lamb survival. Litter size significantly affected lamb survival, although inclusion of birth weight in the model reduced the effect. Weather conditions, as measured by chill index, significantly (P<0.01) affected lamb survival in 1984 but accounted for less variation in 1985 (P<0.05). Lamb survival for ewes was ranked BLM > TD > BD. Maximum survival was achieved at birth weights of 4-5 kg from BD and TD ewes and 5-6 kg from BLM ewes. The L treatment reduced (P<0.01) ewe greasy fleece weight by 0.15 kg but did not affect staple strength. Plasma glucose concentration at the end of treatment was lower (P<0.01) for L ewes, but there was no difference between L and H ewes in late pregnancy. Glucose declined with increasing fetal number. Plasma B-hydroxybutyrate concentration was lower for the H group than for L, and also for BLM than TD and BD ewes (P<0.01).
Booroola ewes in moderate body condition on pasture, were either not supplemented, or supplemented prior to parturition with lupin grain for 9 days in a preliminary experiment, or with lupin or oat grain for 17 days in the main experiment. Measurements included lamb birth weight and survival and, in the main experiment only, ewe milk production and lamb immunoglobulin concentrations. With 9 days of lupin grain supplementation, lamb survival to weaning increased by about 12% (P<0.05), size of litter weaned increased from 1.26 to 1.52 (P<0.01) and lamb birth weight increased by about 0.2 kg (P<0.01). In the main experiment, supplementation with lupins resulted in 95% survival to day 9 of twin-born lambs, compared with 68% for lambs from control and oat-fed ewes (P<0.05). Extra lamb losses, due to starvation in the unsupplemented group, were matched by losses due to dystocia in the fed groups. Lamb birth weights, and ewe milk production and composition, were similar across treatments. During the feeding treatment period, only the lupin supplemented ewes maintained their fat score while the other ewes lost 0.5 of a fat score (P<0.01). Fewer (P<0.1) multiple-born lambs from lupin supplemented ewes had low serum immunoglobulin scores, indicating that the lupin supplement may have affected production or intake of colostrum.
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