Small Ruminant Research最新文献

Data records of 3800 Dorper, Dorper × Menz and Menz lambs born from 2011 to 2023 were used to determine non-genetic factors and to estimate variance components of lamb survival at Debre Birhan Agricultural Research Center, Ethiopia. The traits investigated were lamb survival from birth to 90, 180, 365 and 90 to 180 days of age. The data was subjected to analysis using the Weibull proportional hazard model. The mortality rates of lambs at different age intervals (90, 180, 365, and 90 to 180 days) were determined for three breeds: Dorper, Dorper × Menz, and Menz. The respective mortality rates for each breed were as follows: 23.96%, 36.85%, 48.72%, and 15.47% for Dorper; 23.64%, 37.33%, 56.32%, and 17.00% for Dorper × Menz; and 12.98%, 23.44%, 39.31%, and 11.44% for Menz respectively. Breed of lamb, year of birth and lamb weight at birth significantly (P < 0.05) affected risk of lamb mortality during all the periods studied. On the other hand, except from 90 to 180 days of age, lamb inbreeding coefficient, birth type, parity of dam and season of birth significantly (P < 0.05) affected lamb risk of death at all studied periods. However, sex of lamb had a significant (P < 0.05) effect during birth to yearling and weaning to six months of age. Dorper and Dorper × Menz lambs had higher (P < 0.05) risk of death compared with the local breed (Menz lamb). The likelihood of mortality significantly decreased as the weight of the lamb at birth increased, transitioning from very low values (less than 2 kg) to higher values (4.00 kg and above). Lambs with a higher inbreeding coefficient (above 6.25%) exhibited the highest risk of death (2.13) compared to lambs with a zero inbreeding coefficient. Lambs born from younger (nulliparous) and older dams (5 parity and above) faced a higher risk of death. The heritability estimates for lamb survival during the birth to yearling age period ranged from 0.004 for Menz to 0.25 for Dorper, indicating variability in the genetic influence on this trait between the two breeds. While direct selection for lamb survival may be challenging due to low heritability specifically for Menz sheep, implementing measures such as improved lamb care, accounting for seasonal variations, and indirect selection based on birth weight can lead to notable improvements in lamb survival rates within the research center. The significant and alarming lamb mortality rates observed in the research center necessitate the immediate implementation of measures and strategies.

This study compared the effect of either keeping South African Mutton Merino (SAMM) ram lambs intact, or castrated with age applicable methods on their carcass characteristics, meat quality and fatty acid composition of subcutaneous fat (SCF) and intramuscular fat (IMF). Ten lambs per treatment were castrated early at one week of age (EAR) with an elastrator band (4.4 kg ± 0.78 kg: mean ± SD), another 10 lambs at eight weeks of age (late castration - LAT) with a burdizzo (23.6 kg ± 2.26 kg: mean ± SD), whereas another ten lambs were left intact (CON). The two castration methods used were based on cost, ethical prescriptions and to mimic commercial operations. The lambs were housed individually in 30 pens (1.404 m²) for the duration of the study. Animals were housed on an elevated slatted wooden floor in the same metabolic building with an extractor fan to promote ventilation. At the start of the feeding trial, the age of the lambs was on average two and a half months with a live weight of 24.3 kg ± 4.10 kg (mean ± SD). The lambs were fed a standard commercial finishing diet for 67 days and slaughtered when they reached approximately 44.2 kg ± 6.35 kg (mean ± SD) live weight. After slaughter, carcass characteristics (cold carcass) and meat quality were evaluated. The left 3-rib cut was dissected (9th through 11th rib) and the muscle percentage for CON lambs was higher compared to both EAR and LAT lambs. Therefore, CON lambs produced leaner carcasses compared to EAR and LAT lambs. Castration status had no effect on meat Warner-Bratzler shear force (WBSF), consumer sensory analysis nor colour. For proximate composition, CON lambs had higher moisture compared to LAT lambs while LAT had higher dry matter compared to CON lambs. Both, EAR and LAT lamb’s meat had higher organic matter compared to CON lamb’s meat, but these differences were negligible. For IMF in the longissimus thoracic et lumborum muscle, CON lambs’ meat had higher total PUFA, α-linolenic acid, total PUFA n-6, linoleic acid, PUFA:SFA ratio and PUFA:MUFA ratio than meat from both EAR and LAT lambs. Eicosapentaenoic acid (EPA) and total PUFA n-3 were both higher for meat from CON lambs than LAT lamb’s meat, while palmitic acid and conjugated linoleic acid (CLA) were higher for EAR lamb’s meat than CON lamb’s meat and EAR lambs than LAT lamb’s meat, respectively. For SCF, CON lambs had higher heptadecenoic acid and linolelaidic acid than LAT lambs. The calculated atherogenicity index (AI) of SCF was higher for LAT lambs compared to CON lambs. Limited effects of castration age on the possible health benefits of SAMM lamb meat were proven in the current study. It is however suggested that for a higher production response and carcass muscle content, to either keep SAMM rams intact or at least postpone castration for as long as possible.

In France, among the goat breeders on genetic improvement programs, udder scores are recorded annually on primiparous does. New phenotypes include imbalances of the udder (166,929 records since 2016) and milky cysts (100,079 records since 2018). The objectives of this study were to (1) describe the frequency and intensity of these new phenotypes, (2) evaluate their associations with udder conformation traits, (3) determine their impact on milk somatic cell counts (SCC) and dairy production performance. Udder imbalances were defined using a 4-level grid according to the height difference between udder halves. Milky cysts were described as either isolated or numerous. The data were compared with information on mammary conformation (9 traits, each being evaluated on a scale of 1 to 9 with the exception of the length of the teat), SCC (geometric mean calculated over 250 days of lactation) and milk production performance obtained over a reference period of 250 days. In 90.8% (of the cases, udder imbalances were absent or very small, with the most pronounced imbalances (≥10 cm difference between glands) accounting present in only 1.1% of goats. The greatest deficiencies were associated with low udders and poorly attached udders (fore and rear attachments). SCC increased with the degree of imbalance, from 589,000 to 1349,000 cel/ml between no or slight imbalance and an imbalance of ≥10 cm or more. Milky cysts were recorded in 1.9% of the scored udders. Udders with cysts were characterized by poor fore attachments. Likely of traumatic origin, milky cysts were nevertheless associated with increased SCC: 646,000 vs. 912,000 cells/ml for no cysts and numerous cysts, respectively. The hypothesis of a deterioration in milking conditions for the most severe cases remains to be assessed. Finally, impacts on milk production or protein and fat contents reached - 14.1%, - 9.7% and −12.9% respectively for unbalanced udders compared to balanced ones. They were not noticeable for the presence of cysts.