Abstract:
An experiment was studied to investigate influences of full fat soybean (FFS) diets on follicular development and concentration of progesterone in the postpartum crossbred dairy cows. Six multiparous and nine primiparous 87.5% crossbred Friesian cows were assigned randomly to a 3 x 2 factorial arrangement to evaluate 3 groups of diets which began after calving to 8 weeks postpartum. Cows received total mixed ration consisted of a 39:61 corn silage:concentrate ratio with 0, 18 or 24% of DM diet as FFS. All diets which were isonitrogenous and isoenergetic and contained 1.4, 4.5 or 5.9%EE, respectively. Dry matter intake (DMI), milk yield, body condition score (BCS) and body weight (BW) were recorded. Milk samples and rumen fluid were collected to analyze milk composition and volatile fatty acids (VFA). Blood plasma was analyzed for glucose, non esterified fatty acid (NEFA) and progesterone (P4) concentrations. Follicular development was monitored by ultrasonography.
Results of the experiment showed that average DMI, BCS, BW, milk composition, ruminal pH and VFA concentration were not significantly different (p>0.05) among dietary groups. Average milk yield during the 2nd month postpartum and all experiment period were significant difference (p<0.05) among dietary groups. Average milk yield of 0, 18%FFS versus 24%FFS groups were 16.8, 17.8 versus 20.9 and 16.3, 17.1 versus 19.4 kg/d, respectively. Average EB was more negative (P<0.05) in multiparous cows fed 18%FFS diet than multiparous cows fed 0%FFS diet. The concentration of plasma glucose, NEFA and follicular development did not differ (p>0.05) among dietary groups. However the concentration of plasma P4 in 0 and 18%FFS groups were greater (p<0.01) than 24%FFS group.
Augmentation fat supply in form of oilseed from FFS did not influence on follicular development in crossbred Friesian cows but supplementation FFS at 24% of diet apparently led to increase milk yield while it enhanced negative EB (NEB). This greater NEB led to reduce plasma P4 significantly when compared to cows fed 0 and 18% FFS diets.
