Grape juice concentrate as a feed for beef cattle

Abstract

This paper explores the possibility of using surplus grape juice as a feed for beef cattle. Concentration (× 3) of the original juice gives grape juice concentrate (GJC) which has a dry matter content (DM) of 600–650 g kg −1. Most of the DM (c. 920 g kg −1) consists of glucose and fructose, both the crude protein (< 20 g kg −1 DM) and ash contents are low and the pH is 3.0. In 3 trials with growing beef cattle the GJC proved to be palatable and to stimulate dry matter intake, and when it was gradually introduced to the animals' diets, no health problems were encountered. In Trial 1, Hereford × Friesian heifers ( n = 24) between 300 kg live weight and slaughter, showed similar growth rates (1.02 vs. 0.95 SED 0.023 kg day −1) when fed on a conventional grass hay + barley diet or a diet in which GJC was available ad libitum and contributed 0.40 of overall DM intake. No significant treatment differences were seen in slaughter weights, killing out proportions, carcass weights, carcass classification, carcass measurements, sample joint dissection or meat sample sensory evaluation. In Trial 2, 20 Friesian steers were individually fed between 400 kg and slaughter on either a complete diet, based upon barley straw and cereals, or on similar diets containing up to 40% GJC. Over all treatments, growth rates averaged 1.00 kg day −1 and the regression of daily live-weight gain on the proportion of GJC in the diet gave a value of +0.015 (± 0.02) kg per 10% increase in GJC inclusion, which was non-significant. As with Trial 1, the post-slaughter data showed no consistent significant treatment effects. Trial 3, with 32 Friesian bulls of an initial live weight of 115 kg, showed that when fed in conjunction with the complete diet used in Trial 2, ad libitum GJC gave similar growth rates irrespective of whether it contained urea at a rate of 0, 20 or 40 g kg −1. The control animals had a growth rate of 1.30 kg day −1, which did not differ significantly from the 3 GJC treatments (1.23, 1.29, 1.26, SED = 0.057) which had an average GJC intake of 0.21 of the total DM intake. Thus overall, the trials have shown that GJC ca successfully be incorporated at moderately high levels into the diets of beef cattle.