Effect of Palpable Udder Defects on Milk Yield, Somatic Cell Count, and Milk Composition in Non-Dairy Ewes

In non-dairy ewes, udder defects hinder the survival and weight gain of their pre-weaned lambs. The objectives of this study were to determine the effects of palpable udder defects on milk yield, somatic cell count (SCC), and milk composition in non-dairy Romney ewes. Ewes with a history of udder defects or normal udders were selected for the study. Of a total of 48 ewes that lambed, 30 ewes reared at least one lamb, and were milked six times, once weekly, for the first six weeks of lactation. Udder halves were palpated and scored at each milking event. Multivariate linear mixed models examined the impacts of udder defects on udder-half and whole-udder milk yield, SCC, and milk composition (fat, protein, lactose, total solids, and solids non-fat (SNF)). Across the six examinations, 24.7% of the total 352 udder-half examinations were observed to be defective. Udder halves that were defective at least once produced on average 57.9% less (p < 0.05) milk than normal udder halves, while normal udder halves with a contralateral defective half yielded 33.5% more (p < 0.05) milk than normal udder halves. Successive occurrence of both hard and lump udder defect categories in an udder-half, udder defect detection early in lactation, and a high frequency of udder defect detection were all associated with udder-half milk yield loss (p < 0.05). At the whole-udder level, no differences in milk yield (p > 0.05) were observed between those with one udder-half defective and both normal udder-halves. However, udders in which one udder half was categorised as hard but progressed to lump and remained as lump until 42 days of lactation produced less (p < 0.05) milk compared with normal udders. With the exception of SNF, there were no significant associations (p > 0.05) between milk composition parameters and udder defect. Overall, these findings emphasise the importance of udder health in non-dairy ewes and the potential effect of udder defects on their lambs.

Associations among Mammary Ultrasound Measurements, Milk Yield of Non-Dairy Ewe Lambs and the Growth of Their Single Lambs

Mammary cistern size was positively correlated with milk yield of mature dairy ewes, but the association in ewe lambs is unknown. This experiment aimed to examine the associations between mammary ultrasound measurements and the milk yield of ewe lambs at one year of age and to determine the accuracy of using maternal mammary ultrasound to predict single lamb growth rates. Single-bearing ewe lambs (n = 45) were randomly selected and 30 were milked once at weeks three (W3), five (W5), and seven (W7) of lactation. Mammary ultrasound scans were performed at day 110 of pregnancy, W3, W5, W7, and weaning (L69). Single lambs (n = 30) were weighed at birth and at each mammary scanning event. Udder measurements explained 26.8%, 21.4%, and 38.4% of the variation in milk yield at W3, W5 and W7, respectively, and 63.5% and 36.4% of the variation in single lamb growth to W3 and to L69. This ultrasound technique was more accurate in predicting single lamb growth to W3 than milk yield and may enable the identification of pregnant ewe lambs whose progeny would have greater growth rates. More research is needed to identify accurate indicators of superior milk yield and determine whether ultrasound could be used to select ewe lambs.

Lactation curve, milk production of Pelibuey ewes and preweaning growth rate of the lambs

Objective: To estimate the lactation curve and milk production of Pelibuey ewes andthe relationship with preweaning growth rate of the lambs.Design/methodology/approach: Forty five Pelibuey ewes were milked during 70days in Montecillo, México, in 2018, to estimate daily and total milk production. Thelactation curve was fitted with the incomplete gamma function. In addition, the effectsof type of birth and ewe weight at milking on milk production were analyzed, andcorrelations were calculated between ewe milk production and growth rate of thelambs, per week and for the entire lactation Results: A “typical” lactation curve was found, average ewe milk production for theentire lactation, weighted for the number of lambs suckling, was 131±8 L, with444±24 g d -1 . Ewe weight at milking had an effect (p&lt;0.01) on milk production.Positive correlations were found (p&lt;0.05) between ewe milk production andpreweaning growth rate of the lambs.Limitations on study/implications: There is a strong dependency of the lambs forthe milk production of the Pelibuey ewe, a factor of great relevance so that lambs cangain body weight and survive during lactation.Findings/conclusions: Pelibuey ewes produce less milk than dairy ewes. Therefore,lambs should be weaned at a maximum of 10 weeks of lactation.

Towards a Sustainable Reproduction Management of Dairy Sheep: Glycerol-Based Formulations as Alternative to eCG in Milked Ewes Mated at the End of Anoestrus Period

This study investigated whether the administration of equine chorionic gonadotrophin (eCG) in a protocol to induce and synchronize ovulations before mating could be replaced by the administration of glycerol-based formulations in milked ewes at the end of their seasonal anoestrus. Forty-eight late-lactation dairy ewes of the Sarda breed were synchronized using sponges impregnated with progestogen and then joined with fertile rams (day (D) 0, ram introduction). From D−4 to D−1, the ewes received by gavage either 100 mL of a glucogenic mixture (70% glycerol, 20% propylene glycol and 10% water; GLU group; n = 24) or 100 mL of water (GON group; n = 24) twice daily. Moreover, on the day of sponge withdrawal (D−1), GON ewes received 200 IU of eCG. There were no differences in reproductive performances between groups. GLU ewes showed higher glycemia (p < 0.001), insulinemia (p < 0.05), plasma glycerol (p < 0.001), triglycerides (p < 0.001) and lower cholesterol (p < 0.001), non-esterified fatty acids (NEFA; p < 0.05) and urea (p < 0.001). Plasma osmolality was higher in GLU but only 4 h after dosing (p < 0.001). Milk yield and milk composition were not affected by the treatments with exception of milk glycerol (p < 0.001) and milk urea (p < 0.001), which were higher and lower in GLU than GON ewes, respectively. In conclusion, the administration of the glucogenic mixture to late lactation dairy ewes at the end of anoestrus period resulted in reproductive responses as good as the ones obtained by the eCG treatment, suggesting that the objective of a sustainable reproductive management of dairy sheep can be successfully pursued.