Different fibre sources in dairy ass’s diet: effects on body condition and plasma leptin level

Aiming to investigate on the relationships between milk yield and donkey nutritional status, the effects of different fibre sources in concentrate for dairy asses were investigated on asses's body condition and plasma leptin level. Sixteen not pregnant pluriparous asses (body weight: 300 +/- 35 kg; milk yield per milking: 925.0 +/-331.5 g at 125 +/- 48 days of lactation), adapted to machine milking routine, were divided into two groups fed two isoenergetic and isonitrogenous mixed feed including either wheat bran (group A) or dehydrated beet pulp (group B). During the experimental period, lasted 84 days, asses were daily fed 8 kg coarse hay and 2.5 kg mixed feed (A or B); individuaI milk yield was recorded daily while body condition score and plasma leptin levels were assayed every 21 days. Throughout the experiment alI the animals remained healthy, maintained constant the dietary intake and produced normal faeces. Asses's body condition score, always within a 3.0 -3.25 score, did not differ between the two groups while statistical analysis pointed out a significant variation during lactation. Plasma leptin levels, measured for the first time in lactating asses, ranged between 2.95 ng HE/ml and 14.7 ng HE/rnL. Although the investigated fibre sources did not affect plasma leptin level (A: 7.77 :t 0.44 ng HE/mL; B: 6.76 :t 0.45 ng HE/mL), significant higher level were observed at the end oflactation and were related to body condition score values (R2= 0.42; P<0.01).