The liver of the cow is a cross-road of nitrogen metabolism in dairy cows. Urea is synthesized in the liver as a results of unused degradable protein in the rumen, the absorption of excess amino acids from rumen undegradable protein, and from the catabolism of amino acids that are not utilized for productive purposes. Dietary crude protein (CP, % of DM) is the one single dietary factor most clo...

degradation of dry matter (dm) and nitrogen (n) in fresh or frozen-thawed alfalfa and ryegrass was studied by using in situ technique. the forages were labeled with 15n during growth in a glasshouse, harvested at similar growth phase, and fresh (f) or frozen-thawed (ft) samples were incubated in the rumen of 3 sheep. there was no difference (p>0.05) between forage type (s) for the immediately s...

Dairy cows utilize feed crude protein (CP; N x 6.25) with much greater efficiency than other ruminant livestock but still excrete about 2-3 times more N in manure than in milk. This contributes to increased costs of milk production and to environmental N pollution. The function of dietary CP is to supply the cow with metabolizable protein (MP) as absorbed amino acids (AA) but any extra dietary ...

The aim of this study was to evaluate the effects of balancing low protein diets for methionine and lysine on performance of early lactation Holstein cows under hot environmental temperature. Twenty one multiparous Holstein cows in early lactation were allocated to three experimental rations including, 1) High protein ration with 17.5% CP, 2) Medium protein ration with 16% CP and 12 g/d rumen p...

Management of metabolic hydrogen ([H]) in the rumen has been identified as an important consideration when reducing ruminant CH4 emissions. However, little is known about hydrogen flux and microbial rumen population responses to CH4 inhibition when animals are fed with slowly degradable diets. The effects of the anti-methanogenic compound, chloroform, on rumen fermentation, microbial ecology, a...

One primiparous and 3 multiparous lactating Holstein cows fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design to determine the efficacy of adding urea to a corn silage-based diet on ruminal fermentation and microbial protein synthesis. Dietary treatments were 0, 0.3, 0.6, and 0.9% urea in diet dry matter (DM); urea was manually top dressed and incorporated into th...

Abstract The performance, economic, and environmental consequences of feeding rumen degradable protein (RDP) levels above below calculated maximum energy-dependent microbial crude (MCP) synthesis potential are poorly understood. Yearling steers (n = 54; initial BW 484.1 ± 26.03 kg) were assigned to one two pens that each contained an automated head chamber system (GreenFeed; C-Lock Inc., Rapid ...

Ruminant feed evaluation systems use constant minimum requirements of rumen-degradable protein (RDP) and often relate this to apparently degradable organic matter (OM). However, studies with tropical forages indicate that RDP: apparently degraded OM might not be constant across high-fiber diets. This was tested with semi-continuous ruminal cultures (Rusitec) using dried contrasting low-protein ...

This study was conducted to determine in vitro crude protein degradation (IVDP) parameters and effective crude protein degradability (EPD) of various feeds using the modified in vitro gas production (GP) technique. Feed samples were alfalfa hay, soybean meal, soybean, rapeseed meal, sunflower meal and fish meal. Rumen fluid was collected before the morning feeding from four rumen fistulated lam...