Somatotropin and fat administration to lactating dairy buffalo: effects on milk production and plasma leptin

The aims of this study were to determine the effects of somatotropin (bST) and dietary Fat administration on milk production, plasma leptin, and selected plasma lipid parameters in dairy buffalo. Forty lactating Italian river dairy buffalo in mid to late lactation were randomly divided into 4 groups: Control, Fat (0.3 kg/d of rumen-protected fat), bST (320 mg/3wk of slow release bST for 4 cycles) and bST+Fat. Milk production was measured weekly. Blood samples were collected weekly at 14.00h and plasma analyzed for leptin, NEFA and triglyceride. Somatotropin administration increased (P<.01) milk yield (6.76, 7.55, 9.03, and 8.99 kg/d in control, Fat, bST and bST+Fat respectively), whereas milk composition was unaffected by treatments. Although plasma NEFA was unaffected by treatments, mean plasma leptin (2.33, 2.81, 2.28, 3.32 microg/l; P<.01) and triglyceride (309, 370, 321, 351mmol/l; P<.05) were increased by Fat supplementation. Results herein presented confirmed a galactopoetic effect of bST in lactating dairy buffalo. On the other hand increased plasma leptin level observed in fat supplemented buffalo pcould confirm that, like in other mammals, plasma leptin is related to dietary fat composition and to the nutritional status of the animal.