Changes in the composition and fatty acid profile of Najdi ewes’ milk before and after weaning

This trial aimed to study the changes in the yield, composition, and fatty acid (FA) profile of ewes’ milk during suckling and milking periods. Nineteen multiparous Najdi ewes were kept under identical management and feeding conditions during a 12-week trial that was divided into two periods. Milk samples were collected on each sampling day from the total yield during the suckling (3rd, 6th, and 9th week) and milking (12th week) periods. The milk yield and the total solids, fat, protein, and lactose contents of the milk remained constant throughout the suckling weeks, but the protein content increased and milk yield and lactose content decreased after weaning. There were no differences in milk saturated FA (SFA), unsaturated FA (UFA), and monounsaturated FA (MUFA) contents during the suckling and milking periods, whereas the polyunsaturated FA content increased during the milking period. There were no differences in the individual milk SFA during the weeks of suckling, but the contents of caproic acid (C6:0), caprylic acid (C8:0), margaric acid (C17:0), and stearic acid (C18:0) decreased. However, myristic acid (C14:0), lauric acid (C12:0), and isomers of pentadecanoic (C15:0) acid increased during the milking period. The percentage of vaccenic acid (C18:1△11t), rumenic acid (C18:2△9c,11t; conjugated linoleic acid (CLA)), ω-3 FA group, and the atherogenicity index did not differ during the suckling period, but increased after weaning in the 12th week of lactation. This study demonstrated that weaning lambs in Najdi ewes is probably a factor that strongly affects milk traits by changing yield, composition, and FA profile.Keywords: CLA, dairy ewes, milk fat, milk yield, stage of lactatio

Environmental and genetic causes of variation in growth patterns of Najdi sheep from birth to maturity

Data on 23 males and 21 females we re analyzed to evaluate the effects of month of birth, age of dam, age of animal and sex on growth pattern; of various body characters of Najdi sheep. Bodycharac-ters used for analysis were body weight, body length, height at withers and chest girth taken at 3 monthly intervals from birth up to 36-month of age. Resu'ts showed that month of birth was a significant (P < 0.01) source of variation for various body characters Jp to 9-month of age. The effects of age of dam and age of animal within each interval, were significant IP < 0.01) on all body characters at birth and at 3-month of age. At 6-month of age, sex showed significan effects on all body characters except for the body length. Thereafter, the males became longer (P < 0.01) than females at 12-month of age. Fitting Brody's equation to a least-squares mean weight and to the actual observed mean weight at each age consistently underestimated the birth weights by 40% and 25.5% for males and by 46% and 44.5% for females, respectively. The values for asymptotic body weights were close to those of 36-month of age. Also, the Brody model did not yield significant differences for the various body measurements in comparison with the actual observed estimates from birth through maturity