Straw feeding trials with sheep

Abstract

The cereal industry produces a lot of by-products such as barley, oat and wheat straws, Jawar and Bajara straws. These straws have high contents of crude fibre and low protein. When they are fed as such, the animal does not get enough energy to maintain body weight. On the contrary loss in body tissue takes place. Nevertheless, these by-products are an important part of animal feed, especially in dry conditions when green forage is not available.

In such circumstances the better utilization of roughages depends on some additives. It has been known that ruminant depends on microbial population for roughage digestion. These micro-organisms and protozoa use nitrogen for their development from protein, amino acids, nitrate and urea.

Overseas, urea as a non-proteinous, nitrogenous (NPN) substance, and being a cheaper source of nitrogen, has been used to replace a portion of the protein in the ruminant digestion. Urea nitrogen is utilized in the formation of body protein by ruminants (Watson, et al 1944). In New Zealand, in this field, not much work has been done for the utilization of roughage with urea. Therefore this experiment was conducted to find out the extent to which various treatments and supplements, including NPN, may be of practical use in this part of the world.

The experiment consisted of a series of trials of an exploratory nature. Local straws - barley straw, rye grass straw and pea straw formed the basal diets. Comparisons were made between these straws and lucerne hay - the latter known to be a good maintenance food.

To find out whether treatment of the straw influenced intake, hammer-milled and chaffed barley straw were compared with long barley straw. The effect of various supplements was also studied. The supplements used were dry molasses alone, urea/molasses, rumevite, and peas.

The experiment was also conducted to observe the rate of passage with different foodstuffs.

In ruminants the main energy source is volatile tatty acids which are produced from the roughages as well as concentrate rations. Different roughages produce different proportions of VFA in the rumen. The experiment was also conducted to find the amount of VFA production with barley straw long alone, with urea molasses, with rumevite block and lucerne hay.