Abstract

The objectives of this study were to investigate whether or not consumption of protected glutamine  during transition period would affect biomarkers of oxidative stress and milk production. 36 pregnant Holstein dairy cattle were chosen according to body condition score (BCS) and their parity, after which they were classified into two groups with regards to their expecting calving and parity. Group B received daily (100 g/day) protected glutamine with formaldehyde for 21 days before calving, while Group A received basic ration only. After calving, Group B was divided into two categories; one category continued to receive glutamine (100 g/day) for 21 days (BFAF, n = 9), while the other did not(BFAN, n = 9). Also, Group A was classified into two categories; one received glutamine (100 g/day)(BNAF, n = 9), while the other did not (BNAN, n = 9). There were no any significant differences and interaction among treatments in dry matter intake of 0, +7 and +14 after calving, but dry matter intake of d +21 was affected by post partum glutamine feeding and it increased in (BFAF) and (BNAF) as compared to (BFAN) (19.31 and 19.26 versus 18.68 respectively) (p≤0.05). Milk yield and its components did not differ in the treatments. The total antioxidant status (TAS mmol/L) influenced by postpartum glutamine feeding on +7, +14 and +21 after calving was most for (BFAF) and (BNAF) as compared to BFAN and BNAN (p≤0.05). The plasma glutathione peroxidase activity (PGX units/ml PCV) was affected by pre and postpartum treatments and glutamine supplementation had increment effects on (PGX) at 0, +7 and +21 days after parturition. The results suggested that glutamine feeding could enhance total antioxidant status and plasma glutathione peroxidase activity in fresh Holstein dairy cows and the best level of formaldehyde for protection glutamine is 1%.

Key words: Holstein cow, oxidative stress, transition period, glutamine.

Abbreviation

BFAF, Before calving feeding after calving Feeding; BFAN, before calving feeding after calving not feeding; BNAF, before calving not feeding after calving feeding; BNAN, before calving not feeding after calving not feeding.