Efficient protein utilization from different sources of feedstuff for dairy cattle

Abstract

Dietary crude protein contains nitrogen (N) which provides amino acids (AA) for maintenance growth and milk production. In the other hand, providing N in excess amount could indirectly be harmful to human health and also polluted the environment. Dairy farmers should consider carefully to manage excess N. However, possible way in practice is to feed animals more efficiency and accurately in dairy farms. By following the German protein evaluation system of the Committee for Standard Requirement of the Society for Physiology of Nutrient (1997) series of experiments were carried out to find out the amounts of the utilizable crude protein (nXP) at duodenum by using different sources of feedstuff's, namely; dried malt residue, soy sauce residue and soybean hulls. Four crossbred native x Holstein Friesian heifers, fitted with the fistula in the rumen and the cannulas in the duodenum and ileum were used in the experiments. Titanium oxide (TiO2) was used as marker for the experiments. In experiment I with 0, 20, 30 and 40 percent of dried malt residue in the diets, it was found out that the crude protein (nXP) reaching the duodenum were 610, 78, 606.82, 578.25 and 608.35 g/day, respectively. In experiment II, the soy sauce residue was supplemented at 0, 10, 20 and 30 percent in the experimental diets. The results showed that crude protein (nXP) entering the duodenum was 639.55, 676.93, 639.65 and 658.58 g/day, respectively. In experiment III, the soybean hull was supplemented at 0, 20, 40 and 60 percent in the experimental diets. The results from this experiment showed that crude protein (nXP) could reach the duodenum at the amount of 1037.85, 996.11, 1,062.89 and 1,672.76 g/day, respectively. The ammonia nitrogen level and the amount of volatile fatty acid measured in all 3 experiments were shown to be sufficiently supply for the rumen microbes. The amount of utilizable crude protein at the duodenum by using dried malt residue as a protein source in experiment I was well enough for maintenance (320 g.) and for producing about 3.54 kg of milk. In experiment II, Maintenance (320g nXP) and 3.15 kg of milk. Only in experiment III with the supplementation of soybean hulls in the experimental diets gave a relatively higher amount of utilizable crude protein for maintenance and enough for about 8.7 - 16.5 kg of milk.