Behavioural and growth effect of oral administration of rumen protected tryptophan on weanling beef calves
1998
Nakanishi, Y. (Kagoshima Univ. (Japan). Faculty of Agriculture) | Shigemori, K. | Yanagita, K. | Mieno, M. | Manda, M.
This paper examines the effect of orally administered tryptophan on behaviour, growth rate and feed utilization of beef calves during 14 days postweaning at 3 months of age. Twenty-two Japanese Black calves were used in the following two experiments; 12 calves in Exp.1 and 10 animals in Exp.2. After weaning an oral tryptophan (160 mg kg(-1) of BW, including 30% L-tryptophan) was given once a day for 14 consecutive days in Exp.1, whereas it was done on alternate days in Exp.2. In Exp.1, tryptophan calves spent significantly more time lying than control (P0.05) and they tended to spend less time in locomotion and exploration. Agonistic interactions, social investigation, vocalization, play )mostly mock fighting) and mounting were decreased by tryptophan doses (P0.05). Average daily weight gain (ADG) and feed utilization of the tryptophan calves did not differ significantly from those of controls. In Exp.2, eating and lying behaviours were increased by tryptophan doses (P0.05). The social behaviour showed a similar pattern to that in Exp.1. The ADG of the tryptophan calves was greater than that of controls (1.5 kg vs. 0.8 kg, P0.01). Feed utilization was not significantly increased by the tryptophan dose even though it appeared to be higher in tryptophan calves than controls. The present findings suggest that oral administrations of tryptophan have a significant sedative effect on agonistic behaviour and this may lead to a higher feed utilization
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