Energy and Nitrogen Utilization of High Versus Low Producing Dairy Cows

Abstract

Six high and 6 low producing cows were fed corn silage, alfalfa hay, corn, and soybean meal diets to evaluate the cow's ability to metabolize energy and N. High producers consumed more feed and gave more milk than low producers. Energy digestibility (.70), conversion of digestible to metabolizable energy (.90), and absorption of N (.70) were not different between groups. For low producers, heat production (249 kcal/kg BW.75) and loss of metabolizable energy as heat (.62) were greater than for high producers (238 kcal/kg BW.75 and .53), suggesting a less efficient intermediary metabolism of the former. Body composition was unaffected by treatment. Body fat mobilized during periods 1, 2, and 3 was replaced during period 4. Change in body energy (fat) and change in energy balance (calorimetric) data were in the same direction, but absolute values did not agree; change in energy as body fat lagged behind change in energy balance determined by calorimetry. Body protein was used in early lactation and was replaced immediately in spite of negative energy balance; this suggests that protein (amino acids) may play a significant role in meeting short-term energy needs during the first few weeks of lactation.

Feed conversion efficiency in dairy cows: Repeatability, variation in digestion and metabolism of energy and nitrogen, and ruminal methanogens

“…Daily expenditure for NE M did not differ between the 2 groups, but expenditure as milk NE L was greater and expenditure as NE G was lower for highcompared with low-FCE cows. Also, in our trial, heat production averaged 39.4 ± 4.91 Mcal/d, which was comparable to the 35.3 Mcal/d reported in Tine et al (2001) for cows at similar production levels, but higher than the 26.8 and 30.7 Mcal/d reported in Belyea and Adams (1990) and Reynolds et al (2001), respectively, for lower-producing cows. Greater DMI (23.6 vs. 19.5 kg/d; Table 5) should have led to greater heat production for high-compared with low-FCE cows.…”

Energy and nitrogen metabolism and insulin response to glucose challenge in lactating German Holstein and Charolais heifers

“…On the other hand, nutrient digestibility, with the exception of crude fiber, showed no differences between breeds. There seems to be no differences in nutrient digestibility between dairy and beef cows (Hart et al, 1978) and between high versus low producing dairy cows (Belyea and Adams, 1990). The higher digestibility of crude fiber found in Charolais could be attributed to the lower nutrition level (Gabel et al, 2003), which allows a longer retention time of feed particles in the digestive tract.…”

Dietary Energy Source in Dairy Cows in Early Lactation: Metabolites and Metabolic Hormones

“…First, dairy cows in early lactation exhibit incomplete oxidation of fatty acids as indicated by high concentrations of ketone bodies (Guretzky et al, 2006). The second alternative pathway for mobilized NEFA is incorporation of NEFA into milk fat, directly or indirectly via esterification to very low density lipoproteins (VLDL), which causes an increase in long-chain fatty acids in milk (Belyea and Adams, 1990). The third alternative for NEFA is esterification to TAG in the liver, possibly causing a fatty liver (Bobe et al, 2004).…”