تأثیر افزایش سطوح انرژی و پروتئین متابولیسمی در گامه انتهایی آبستنی بر رشد و تکامل پستان بزهای سیستانی

The aim of this study was to consider effect of increasing metabolizable energy and protein during late pregnancy on mammary growth and development in sistani goats. Twenty eight pregnant sistani goats with same average body weight and 2 year old age were selected and randomly assigned to four groups at beginning of late pregnancy period (d 100 of pregnancy): 1- Control group with recommendation level of metabolizable energy and protein according to NRC, 2- group with 10 % greater level of metabolizable energy, 3- group with 10 % greater level of metabolizable protein and 4- group with 10 % greater level of metabolizable energy and protein. After two month feeding, mammary samples were removed by biopsy 24-36 h after parturition to consider mammary histological parameters. Results showed number of epithelial cells were greater in goats fed diets with 10 % greater metabolizable energy and protein both compared to control group (35.8±3.70 vs. 26.4±2.64), but there was no difference among control groups and groups with 10 % greater metabolizable energy or 10%  greater metabolizable protein alone. Epithelium area (µm) affected by diets and were greater in groups with 10% greater metabolizable energy and protein compared to control groups (P=0.03). Percentage of stroma affected by diets (P=0.001) and were decreased by increasing metabolizable energy, metabolizable protein or both compared to control group. Percentage of epithelium affected by diets (P=0.008) and were greater in groups with greater metabolizable energy and groups with greater metabolizable energy and protein compared to control group. In conclusion increasing 10 % metabolizable energy and protein both during late pregnancy improved mammary growth and development with increasing number and percentage of epithelial cells, increasing alveoli and epithelium area and decreasing percentage of stroma in sistani goats that could have positive effect of cololstrum production and milk yiled in subsequent lactation period.