Abstract
This study investigated the effect of feeding two levels of rumen degradable protein in the rations during different stages of lactation on milk yield and components , twenty four cross breed Awassi ewes (Turkish Awassi × Iraqi Awassi) were used with their single lambs after birth aged 3-5 years, ewes were divided into two groups with average body weights 66.00 ± 2.32 kg and 67.10 ± 2.62 kg respectively, first group was control fed adequate level of degradable protein (10 g / Mj metabolizable energy) and second group fed high level of degradable protein (12.5 g / Mj metablizable energy) , Lactation period had been divided into three stages (early, 1-50 day ), ( mid , 51-100 day) and (late , 101-150 day), ewes were fed twice daily with restricted amount 2 kg in the early and mid and 1.5 kg in late lactation . Results showed that feeding adequate level of rumen degradable protein led to significant ( P< 0.05) increase in milk yield 785 g/day and lactose 5.81% as compared with high level 619 g/day and 5.58% respectively, also milk yield decreased ( P< 0.05) while milk fat increased ( P< 0.05) with advance milk period. Blood parameters were not affected significantly by feeding degradable protein while serum glucose, total protein and albumin decreased (P< 0.05) at late stage of milk production. Best results of interaction for rumen degradable protein and milk stages in milk yield and components yield were noted with feeding adequate level of rumen degradable protein in the early lactation.
Highlights
This study was proposed to evaluate the effect of degradable protein level in Awassi ewes rations in performance during different stages of lactation
Milk lactose increase ( P< 0.05) with feeding adequate level of rumen degradable protein 5.81% as compared high level of degradable protein 5.58%, other milk components especially fat increase but not significantly when ewes fed with adequate level of rumen degradable protein
Data of interaction were investigated that with progress stage of lactation milk yield was higher with feeding adequate level of degradable protein as compared with high level
Summary
The transition and early stage of lactation are critical period of ewes life , so that about third body fat and protein may mobilized to meet the requirements according to their milk production even with good nutrition the shortage in energy inevitability occur especially in the early stage of lactation (6), after that milk production decrease gradually as a result of shrinkage of epithelial cell of mammary gland either because of the lower number of epithelial cell or its activity, this will accompanied with a changes in milk components, the proportions of fat, protein increase while lactose decrease (28), on other hand milk production affect by many factors may the most important are availability of protein, energy and minerals (10), energy deficient and the imbalance in degradable to undegradable protein intake negatively correlated with milk production (24). ميكا جول طاقة ايضية خلال م ارحل اد ارر الحليب المختلفة على انتاج الحليب ومكوناته/تأثير مستوى البروتين المتحلل غم
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