Caracterización del período de acostumbramiento de terneros destetados precozmente: Efecto del uso de aromatizantes sobre la performance animal

Early weaning in beef cattle is a commonly used tool to improve reproductive efficiency and weaning rate; when combined with dry-lot feeding of calves and the transition period to a solid diet is carefully followed will also enhance weaning weight. Use of sensorial additives could represent a strategy to stimulate feed intake and improve adaptation to the new feeding system. The objective of this work was to evaluate the effect of the inclusion of an anise based aromatizer in the total mixed ration on early weaned calves’ performance and behavior in a dry-lot feeding system. The main hypothesis was that inclusion of an aromatizer will improve adaptation to the new feed system, enhancing feed intake, weight gain, and feed conversation ratio. Thirty-two early-weaned female Hereford calves (75 ± 19 days; 85 ± 11 kg), were stratified by body weight and randomly assigned to one of two treatments: 1) total mixed ration with whole oats as a short fiber source without aromatizer (Control; n= 16), and 2) same total mixed ration with the inclusion of an anise based aromatizer (Apetenzyma 2, Norel Animal Nutrition, Madrid, España, 3 g/animal/day) (AROM, n=16). Experiment was conducted at the Unidad de Producción Intensiva de Carne (UPIC), at the Experimental Station Dr. Mario A. Cassinoni (EEMAC), in Paysandú, for 73 days. Each calf was placed in an individual pen provided with feeder, water trough, and shade; and received corresponding treatment since day one. Feed offered was adjusted every day to ensure ad-libitum intake and divided into two equal meals per day. Main variables measured were body weight (BW) every 14 days, without fasting, to estimate average daily gain (ADG, kg/d), daily dry matter intake (DMI, kgDM/d), feed conversion ratio as kg of feed needed to gain one kg of BW (FE, kgDM:kgBW), animal behavior, feed intake rate, water intake, and total tract apparent digestibility using acid insoluble ash as an internal marker. Data was analyzed as a completely randomized design, with calf as the experimental unit. Inclusion of an anise-based aromatizer decreased DMI (4.06 vs 3.76 kg DM/animal/day for Control and AROM, respectively; P=0.01) without statistical differences in ADG (1.02 kg/animal/day; P=0.745) and FE (3.97; P=0.555). Animal behavior showed specific differential responses that were observed across weeks, associated with contrasting environmental conditions; however, these did not translate into sustained improvements in productive performance. In conclusion, in early weaned calves fed in dry lot conditions, it is not necessary to incorporate a feed aromatizer in the diet to promote adaptation to the new solid diet. It is possible to ensure a appropriate performance and feeding efficiency at such a young age when gradual adaptation protocol to the new feeding system is strictly applied.