Effect of level of inclusion and method of presentation of a single distillery by-product on the processes of ingestion of concentrate feeds by horses

Abstract

The eating behaviour of horses offered wheat distiller grains at varying levels in the concentrate was examined in two experiments. The objective of the study was to evaluate the effect of rate of inclusion and presentation (dry vs. soaked) of wheat distiller’s grains, and the responses in behaviour and processes of intake. In both experiments, the rates of inclusion were 1.00:0, 0.75:0.25, 0.50:0.50, 0.25:0.75 and 0:1.00 for wheat distiller’s grains/concentrate, respectively. The various mixtures of concentrate were offered to 10 horses according to two 5×5 Latin squares for 10 min and the rate of eating and processes of ingestion were assessed. When offered at a rate of 0.75 in the dry matter and not soaked, there was a significant reduction ( P<0.01) in the rate of ingestion of DM and chews per kg DM ( P<0.01). However, the rate of ingestion of soaked mixed concentrate declined rapidly ( P<0.01) when the rate of inclusion was greater than 0.5 of the dry matter. The behavioural responses of the animals were commensurate to the observations of rate of eating in the case of non soaked concentrate. When 0.75 of the concentrate DM was replaced with wheat distiller’s grains, a significant increase ( P<0.05) in the incidence of shorter than expected feeding bouts was observed. However if feeding was terminated, reversion of feeding occurred with a mean frequency of 0.767. The rate of cessation of feeding was also increased significantly when 0.75 or all of the concentrate DM was replaced with the distillery by-product. If the concentrate was soaked before offering, there was an increase ( P<0.05) in the number of feeding bouts when 0.25 of the concentrate was replaced with wheat distiller’s grains. However the processes of ingestion were not affected until 0.5 of the concentrate DM was replaced. Cessation of feeding was affected significantly by the previous behaviour ( P<0.001) especially when the animal interacts with the environment and resumption of feeding was reduced significantly ( P<0.01) as the rate of inclusion of wheat distiller’s grains increased. Wheat distiller’s grains can be used as a substitute to other energy and protein feeding-stuffs in the ration of the horse. However the inclusion rate depends on the method of presentation of the feed to the animal. Soaking of the concentrate prior to feeding allowed a reduced level of distillery by-product to be incorporated into the ration. Least cost formulation of concentrates for horses should therefore consider the nutritive composition of the feeding stuff, the potential of the novel feeding-stuff to disrupt behaviour during feeding and the cost of the formulation.