Resumen

BERTIN, O.D; CAMARASA, J.N; SCHENEITER, J.O  y  ZUVILIVIA, J.P. El nabo como recurso forrajero invernal en la producción de carne. RIA. Rev. investig. agropecu. [online]. 2015, vol.41, n.2, pp.155-160. ISSN 1669-2314.

The objective of this study was to evaluate the beef production with forage brassica (Brassica napus x B. oleracea cv Interval) in pure culture and in mix with oats with steers grazing in late winter. The experiment was carried out at the Pergamino Experimental Station of the National Institute of Agricultural Technology, Buenos Aires, Argentina during 2011. The treatments were: 1) pure brassica (Nf) and 2) brassica associated with oats (Nf+A) on alternating lines. Treatments were arranged in a randomized complete blocks experimental design with two replications. Three grazing periods were evaluated (Period 1: from August 16th to September 6 th, Period 2 from September 6 th to October 4 th and Period 3 from October 4 th to October 21 th). Results were analyzed using ANOVA (p < 0.05), with the Infostat software. In the Period 2 animals remained only in Nf+A, so only the Periods 1 and 3 were statistically analyzed. Pre and post - grazing forage masses were measured whereas liveweight was taken at the beginning and at the end in each period. At the beginning and at the end of the experiment Nf samples for nutritive value (CP, NDF and DMDIV) were taken. In order to achieve a similar forage utilization between treatments, a put and take management was used with 4 fixed animals per treatment (Aberdeen Angus breed; initial liveweight (LW): 296 ± 26 kg) and 5% of LW of daily forage on offer. The rainfall during experimental period was 38% lower and the numbers of frosts were 23% higher than the historical average (1910-2011). The nutritive value average of Nf was: 18.6% of CP, 23.9% of NDF and 89.2% of IVDMD. In the Period 1, pre and post - grazing forage masses (2590 kg and 1716 kg DM.ha-1, respectively), daily LW gain (1.3 kg.animal-1.day-1), stocking rate (SR, 6.4 animals.ha-1) and beef production (168 kg.ha-1) were the same in both treatments. In the Period 3, pre and post - grazing forage masses (1175 kg and 538 kg DM.ha-1, respectively), daily LW gain (1.1kg.animal-1.day-1) and beef production (89.1 kg.ha-1) were the same in both treatments. The SR showed a tendency to be greater (p = 0.06, SEM: 0.37) in Nf (6.1 animals.ha-1) in relation to the Nf+A (4.0 animals.ha-1). In the analysis of the results of the 3 periods all together (Periods 1 and 3 in the Nf treatment and Periods 1, 2 and 3 for Nf+A) SR was higher (p< 0.01; SEM: 0.07) in the Nf (6.7 animals.ha-1) than Nf+A (4.5 animals.ha-1) and there was a trend (p = 0.09; SEM: 28.3) to a greater beef production in Nf+A than in Nf (403 and 288 kg.ha-1, respectively), because Nf+A allowed to hold animals during all the experimental period. The results show that brassica associated with oats was a best alternative to cover the deficit of forage to the late winter, because allowed support the animals throughout the cycle and increased beef production. Pure brassica, however, allowed to hold higher stocking rate in periods the better climate.

Palabras clave : Brassica napus x B. oleracea; Rape; Oats; Grazing.

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