Comparison Digestibility, Rumen Fermentation and Protozoa Population in Najdi Goats Fed with Whole Branch of Albizia or Alfalfa Hay

Due to the growing human population, the supply of animal protein for them is considered as an important goal. About 70-60% of the costs of livestock raising is associated with nutrition and one of the most important measures to reduce the cost of feed, is the applying of new materials in the livestock rations. Albizia is a native tree in tropical Africa and Asia, northern Australia and tropical America and also in many tropical and subtropical areas of the world. It could be also used in the diet to reduce the cost of livestock ration, but because of some anti-nutrients substances such as tannins and saponins, may be restricted its use in feed. Many studies have shown that it can be used as a protein and mineral supplement in animal feeds. The aim of the present study was the comparison of the nutritional value of the Albizia with alfalfa hay as sole feed source, in the Najdi goats.
Whole plant of Albizia containing seeds, pods and leaves were collected from ranges of Mollasani-Khuzestan region, and air-dried under shadow. In this experiment, six Najdi goats with an average weight of 31 ± 2.2 kg and 19±2 months old in a completely randomized design was assigned to two experimental diets. The experimental diets only were whole plant of Albizia or alfalfa. The diets was fed 28 days, include 21 days adaptation and 7 days sampling period, for measuring the nutrients digestibility. Chemical composition of experimental samples including: crude protein, ether extract, neutral detergent fiber, acid detergent fiber, dry matter and Tannin was measured according to standard methods. Feed intake, nutrient digestibility, protozoa population and ruminal fermentation (pH and Ammonia nitrogen) and blood parameters (glucose, blood urea nitrogen and cholesterol) were measured according to standard biochemical kits.
According to results detecting of the chemical composition, compared with alfalfa, Albizia contained more protein and ether extract and lower ADF than alfalfa forage. The dry matter intake of the goats which were fed by Albizia were significantly higher than they fed alfalfa (respectively, 1682 and 1326 grams per day), but the digestibility of nutrients were not significantly differed among them. The nutrients intake of diet containing Albizia was higher than alfalfa, due to more DM intake and difference in chemical composition of Albizia than alfalfa hay. As the consumption DM of Albizia and percentage of its NDF and crude protein was higher in comparison with alfalfa hay, so the intake of these nutrients was higher. In this experiment, in spite of presence the tannins in the branches of the Albizia, the nutrients digestibility, did not decreased. In the literatures, usually the tannin mentioned as a reduction factor of nutrients digestibility. But if the diet or its ingredients had high percentage of protein, the negative effect of tannins on the digestibility of nutrients due to its binding with proteins reduced, so perhaps due to the high protein of Albizia, its tannin had no negative impact on nutrients digestibility, in present study. The concentration of ammonia nitrogen and pH of the rumen fluid in diets containing Albizia was significantly lower than hay. Perhaps the reason reduction the concentration of ammonia nitrogen in Albizia diet was due to the tannins in that diet. The researchers reported that tannin sources, reduces the protein degradation and concentration of ammonia nitrogen in the rumen. Glucose and cholesterol concentration were not affected by the treatments, but feeding Albizia decreased the concentration of blood urea nitrogen.
The feeding of Albizia significantly reduced the rumen protozoa population of the goats. Perhaps it was due to the present of tannin and saponin in the Albizia. The negative effect of saponin and tannin on rumen protozoan has been proved.
Therefore, the results of this study were shown that in compared to alfalfa hay, the presence of tannin and saponin of Albizia in diet of goats, had no adverse effect on intake and digestion of nutrients, also has beneficial effects on rumen fermentation as decreasing ruminal ammonia-N concentration, So Albizia can be used as part of the diet of goats, even as replacement for alfalfa hay. Although conducting a performance study to ensure is also recommended.