Comparaison des performances des porcs femelles et mâles castrés selon le plafond de rationnement appliqué en fin d'engraissement (2,4 vs 2,7 kg/j)

Nathalie Quiniou et al., 49es Journées de la Recherche Porcine, Paris, 31 janvier et 1er février 2017, p. 125-126, poster

Le taux de muscle des pièces (TMP) à l'abattage et la plus-value accordée selon ce critère dépendent de la composition du gain de poids pendant la croissance. Le dépôt de gras s'accentue en fin d'engraissement notamment chez les mâles castrés (MC) dont la consommation moyenne journalière (CMJ) spontanée excède celle qui suffit pour maximiser le dépôt de muscle.
Un plan d'alimentation rationné est donc généralement appliqué aux MC, le plus souvent extrapolé aux femelles (F) dès lors qu'elles ne sont pas élevées en loges séparées. Dans l'étude réalisée, les performances obtenues par sexe avec deux plafonds de rationnement sont comparées, puis combinées pour évaluer les performances potentielles de la bande.

ENG

Growth performance and carcass characteristics obtained from gilts and barrows restrictively fed up to different maximum daily feed allowance at the end of the fattening period (2.4 or 2.7 kg/d)

Crossbred (Large White x Landrace) x Piétrain gilts (n = 40) and barrows (n = 40) were studied in a pen equipped with a precision feeding device that allows for feed restriction. Within each gender, pigs were restrictively fed with the same increase in daily allowance (+27 g/d) up to a different plateau: either 2.4 or 2.7 kg/d. Body weight (BW) and daily feed intake (ADFI) were measured individually from 32 to 113 kg on average. Pigs reached the plateau during the finishing period, except for some gilts whose spontaneous feed intake remained below. During this period, the decrease in the plateau value induced a decrease in average daily gain (ADG, P < 0.001) without any significant effect on feed conversion ratio, which was perhaps due to a different partition of energy intake between growth and activity in different treatments. The same carcass leanness was obtained with both plateaus in gilts, and in barrows the value obtained with 2.7 kg/d (59.6 point) was not significantly different from that obtained with 2.4 kg/d (60.0 point).
A combination of different plateaus and genders was performed to calculated average results at the batch level. A plateau fixed at 2.4 kg/d both for gilts and barrows leads to the lowest ADG, whereas feeding the gilts up to 2.7 kg/d and barrows up to 2.4 kg/d seems to be the most interesting compromise that lowers the average ADG less, and allows for an easier final management of the batch, without impairing FCR or carcass leanness. However, differences among combinations remain very small.