Comparison of Cottonseed meal and Fish Meal Fed to Dairy Cows Receiving Rapidly Degradable Diets in Holstein Cows

To compare the relative value of the fish meal and the cottonseed meal in highly fermentable diets (40% forage and 60% concentrate with), eight cows were assigned randomly to diets with 0, 1.5, 3 and 4.5 percent of the fish meal. In the first experiment, the degradability of dry matter and crude protein of the fish meal, the cottonseed meal and concentrate in diets was estimated with different incubation times (0, 4, 8, 12 and 24 h) with fistulated Ghezel sheep fed at maintenance level. The effective degradability of dry matter and the crude protein of fish meal was significantly lower than cottonseed meal (p<0.05). In different concentrates, there was no significant difference in effective degradability of dry matter but with the increase of fish meal the effective degradability of crude protein decreased significantly. In the second experiment, the eight multiparous Holstein cows with the similar milk production (25.37 ± 0.85) were examined in a replicated 4 × 4 Latin square design with the 21-day period. There were no significant differences between the treatments in digestibility of OM, OM and CP, the dry matter intake, 3.2 % FCM, milk fat (%), milk lactose (%), milk total solid (%), and the yield of the milk fat, feed efficiency and body weights. Diets containing fish meal, compared to the control group, significantly higher milk production, milk protein (%), the yield of milk protein and lactose (p < 0.1), but the different levels of fish meal had no significant effect on these factors. The urea pH decreased significantly with the increase of the fish meal but rumen pH and fecal pH were unaffected. The results of the experiment indicated that diets with the 1.5 or 3% fish meal in cows with less than 30 kg milk is recommended.