نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم دامی دانشگاه ارومیه
2 دانشیار گروه علوم دامی/ دانشگاه ارومیه
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: Methionine is the most important essential amino acid in mammals’ nutrition and is used for protein synthesis, growth, milk protein, maintenance, tissue regeneration and reproduction. Protected methionine alone or in combination with lysine increases animal performance. The addition of protected forms of lysine and methionine to the diet of dairy cows in early lactation has the greatest potential to improve milk yield for high-producing cows in early lactation. It seems that investigating the effect of using methionine individually when reducing dietary protein is useful to achieve maximum performance. Therefore, the purpose of this research is to investigate the effect of using protected methionine at different levels of metabolic protein in the diet of heavily pregnant ewes on the performance of ewes and lambs born during the transition period. Therefore, the purpose of this research is to investigate the effect of using protected methionine at different levels of protein in the diet on the performance of ewes Ghezel ewes and lambs born during the transition period
Materials and Methods: This experiment was carried in a 2x2 factorial experiment using 40 ewes heterozygous for Fecb genes with twin pregnancy resulting from estrous synchronization in the reproductive season confirmed by ultrasound with an average age of 2±36 months, the average weight (56±3.2 kg) was done. The experimental design was carried out in a period of 74 days, from 44 days before the expected calving to 30 days after calving (14 days of getting used to the experimental rations and the test site, 30 days before calving and 30 days after calving). The experimental treatments include: 1- Diet with metabolisable protein to the required level without protected methionine, 2- Diet with metabolisable protein to the required level with 6 grams of protected methionine, 3- Diet with 10% more metabolisable protein than required, without protected methionine, 4-diet with 10% of metabolisable protein was more than required along with 6 grams of protected methionine. Weekly milk samples were collected on two consecutive days, in order to evaluate the milk composition, the milk samples of the ewes were analyzed using an infrared milkoScan device. Venous blood samples were collected using venipuncture from ewes and lambs via anti-coagulant containing vacuum tubes, 4 hours after the morning meal, every week through experimental period. In order to investigate the effects of dietary interventions on rumen fermentation parameters, rumen fluid sample was taken 4 hours after morning meal on the last day of the experiment using the esophageal tube method.
Results: Crude protein digestibility increased in ewes consuming feed containing protein at required levels, but, the lowest digestibility coefficient was resulted in ewes receiving 10% protein more than requirement irrespective of methionine supplementation (P<0.05). The digestibility of NDF showed a significant increase with the addition of protected methionine to the diet compared to treatments without methionine supplementation (P<0.05). The birth weight of lambs significantly increased in ewes received extra protein supplemented with rumen protected methionine compared to other treatments. Milk production showed a significant increase in the treatment of consuming 10% more protein supplemented with 6 grams of protected methionine compared to other treatments (P<0.05). Total protein and albumin levels were affected both by dietary protein levels and methionine supplementation. Acetate was the highest in the rumen fluid of ewes fed with basal diet and was reduced in diets with higher protein level (P<0.05).
Conclusion: Results of this study revealed that protected methionine supplementation in late pregnant twin bearing ewes improved plasma parameters, lamb birth weights and increases milk production.
کلیدواژهها [English]
)