The Thai Journal of Veterinary Medicine


The aim of this study was to investigate the effect of dietary polyunsaturated fatty acids (PUFAs) from rubber seed kernel (RSK) on growth performance and reproductive performance in dairy heifers. Twelve healthy and cycling Holstein Friesian dairy heifers were randomly divided into two dietary treatments as control group (TMR without RSK; (mean±SD) 31.82±4.25% PUFAs out of 2.65% total fatty acids) and RSK group (TMR containing RSK at 6.16%; 43.93±1.26% PUFAs out of 3.55% total fatty acids). TMR in both treatments consisted of roughage to concentrate ratio of 70:30 and each dietary treatment was formulated to be isonitrogenous and isocaloric. PUFA intake in the RSK group was significantly higher (p<0.01). Results showed that heifers in the RSK group significantly increased total dry matter (DM) intake, crude protein (CP) intake and ether extract (EE) intake, and also body weight (BW) (p<0.01). However, the concentrations of PUFAs in serum were not different between the groups while the concentrations of serum cholesterol were significantly higher in the RSK group (p<0.01). Serum urea nitrogen (SUN) concentrations and β-hydroxybutyrate (BHBA) concentrations in both groups were in optimal range. During the estrous period, estradiol and progesterone concentrations were not different. In addition, progesterone concentrations during estrous cycles were similar between the groups. No difference between the groups was found on estrous behavior and conception rate. In conclusion, the level of RSK in this study can be used as feedstuff in heifer diet with positive effect on feed intake, nutrient and fatty acid intake, without any effect on reproductive performance.

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