Rumen microbes and microbial protein synthesis in Thai native beef cattle fed with feed blocks supplemented with a urea-calcium sulphate mixture.
The influence of slow-release urea ( urea-calcium sulphate mixture; U-CaS) in feed blocks on rumen micro-organisms, predominant cellulolytic bacteria, microbial protein synthesis and ecology was studied in Thai native beef cattle. Four animals with an initial body weight of 100 ± 3.0 kg were randomly assigned to a 4 × 4 Latin square design with four dietary treatments (U-CaS in iso-nitrogen feed blocks at 0, 120, 150 and 180 g/kg dry matter (DM), respectively; U-CaS replaced urea). After 21 days of experimental feeding, rumen fluid was collected at 0 and 4 h after feeding. The mean intake of feed blocks and other feedstuffs offered (rice straw and concentrates) amounted to 0.3, 2.3 and 0.6 kg DM/day, respectively. Inclusion of U-CaS did not altered pH and temperature in the rumen. However, ruminal NH3-N concentration decreased quadratically (p < 0.05) in response to U-CaS inclusion, with the lowest value at 180 g U-CaS per kg feed block. With inclusion of U-CaS, the populations of rumen bacteria increased quadratically (p < 0.05) and counts of fungal zoospores were linearly enhanced (p < 0.05), being highest at 180 g U-CaS per kg feed block. Supplementation of U-CaS increased the concentration of total bacteria linearly (p < 0.05) and of Fibrobacter succinogenes quadratically (p < 0.05), whereas Ruminococcus flavefaciens and Ruminococcus albus were not affected by dietary treatments. Microbial crude protein yield and efficiency of microbial nitrogen (N) synthesis were linearly increased with different levels of U-CaS addition. Furthermore, current data clearly indicate that inclusion of U-CaS in feed blocks can affect micro-organism diversity and major cellulolytic bacteria.
a Tropical Feed Resources Research and Development Center (TROFREC), Department of Animal Science, Faculty of Agriculture , Khon Kaen University , Khon Kaen , Thailand.
Anusorn
A
Cherdthong
Metha
M
Wanapat
D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena / Q000187:drug effects; D000818:Animals; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development; D002133:Calcium Sulfate / Q000008:administration & dosage / Q000378:metabolism*; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D002149:Energy Intake / Q000187:drug effects; D008297:Male; D012417:Rumen / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology*; D013785:Thailand; D014508:Urea / Q000008:administration & dosage / Q000378:metabolism*
D014508:Urea; D002133:Calcium Sulfate