A comparative analysis of rumen pH, milk production characteristics, and blood metabolites of Holstein cattle fed different forage levels for the establishment of objective indicators of the animal welfare certification standard.

OBJECTIVE: This study was conducted to obtain an objective index that can be quantified and used for establishing an animal welfare certification standard in Korea. For this purpose rumen pH, ruminating time, milk yield, milk quality, and blood components of cows reared in farms feeding high forage level (90%) and farms feeding low forage level (40%) were compared. METHODS: Data on rumen pH, rumination time, milk yield, milk fat ratio, milk protein ratio, and blood metabolism were collected from 12 heads from a welfare farm (forage rate 88.5%) and 13 heads from a conventional farm (forage rate 34.5%) for three days in October 2019. RESULTS: The rumination time was longer in cattle on the welfare farm than on the conventional farm (p<0.01), but ruminal pH fluctuation was greater in the cattle on conventional farm than the welfare farm (p<0.01). Conventional farms with a high ratio of concentrated feed were higher in average daily milk yield than welfare farms, but milk fat and milk production efficiency (milk fat and milk protein corrected milk/total digestible nutrients) was higher in cattle on welfare farms. Blood test results showed a normal range for both farm types, but concentrations of total cholesterol and non-esterified fatty acid were significantly higher in cows from conventional farms with a high milk yield (p<0.01). CONCLUSION: The results of this study confirmed that cows on the animal welfare farm with a high percentage of grass feed had higher milk production efficiency with healthier rumen pH and blood metabolism parameters compared to those on the conventional farm.

Crystallization and preliminary X-ray crystallographic analysis of malonyl-CoA decarboxylase from Rhizobium leguminosarum bv. trifolii.

Malonyl-CoA decarboxylase (MCD), which catalyzes the conversion of malonyl-CoA to acetyl-CoA, is an evolutionarily distinct and highly conserved enzyme. MCD does not share sequence homology with other known decarboxylases, while the enzymes from different species exhibit at least >30% sequence identity to each other. In order to provide a canonical structure of the enzyme for detailed study of its structure-function relationship, the MCD of Rhizobium leguminosarum bv. trifolii was overexpressed and crystallized. The crystals belong to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 133.45, b = 127.10, c = 66.37 A. The asymmetric unit is likely to contain two molecules of MCD (molecular weight of 51 418 Da), with a crystal Volume per protein weight (V(M)) of 2.69 A(3) Da(-1) and a solvent content of about 54.3% by Volume. A native data set to 3.0 A resolution was obtained using a rotating-anode X-ray generator.