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Effect of different feeding strategies on the induction of a durable hyperphagia and spontaneous liver steatosis in mule ducks
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Edité par CCSD -
International audience. Our previous studies showed that Greylag geese can develop a prolonged corn hyperphagia during winter season associated with spontaneous liver steatosis. This study aimed to stimulate a similar behavior in mule ducks. 480 male mule ducks, housed in closed pens of 60 animals each, fed a pelleted diet, were submitted to a gradual time restriction to feed access from 49 to 86 days (d) of age (24h to 15 min of feed access/d) combined with a progressive reduction in day length from 75 to 86 d of age (10 to 7h/d). From 87 d of age animals had access to a 100% corn diet and a 2x2 factorial design was applied with two corn feeding modes (ad libitum AL vs progressive P ) and two corn presentations (whole vs grinded corn). In P groups corn availability was increased by 30 g/d starting at 170 g/d. In AL groups time access to feed was ad libitumthen changed at 90 d (2h availability AM) and 97 d of age (1h AM + 1h PM) to stimulate feed intake. 4 treatments of 2 pens each (n=120) were formed. 40 animals were slaughtered before corn feeding, at 87 d of age, and 25 animals per treatment were slaughtered at 94, 101 and 115 d of age to evaluate body and liver fattening. Feed intake and performances at slaughter were similar for both corn presentation types. AL ducks expressed a brief hyperphagia (570 ± 50 g/d) on d 87, followed by a decrease under 300 g/d. The changes in time access to feed induced brief increases in feed intake on d93 and 97 (369 ± 13 g and 406 ± 35 g respectively). Feed intake of P ducks increased until 97 d of age (406±7 g) then decreased similarly to AL birds. After 101 d of age feed intake reached a basal level (148 ± 38 g/d) regardless of the feeding mode. Regardless of the treatments, liver weight only increased slightly at 94 and 101 d of age compared to 87 d of age (84, 83 and 58 g respectively, P<0.05). This study highlights the rapid adaptation of the mule duck to new feeding strategies and the difficulties to induce a spontaneous liver steatosis.