Maintenance energy requirements of beef cows and relationship with cow and calf performance, metabolic hormones, and functional proteins1,2

Abstract

Gestating Angus, nonlactating, spring-calving cows were used to determine variation in maintenance energy requirements (MR); to evaluate the relationship among MR and cow and calf performance, plasma concentrations of IGF-I, T4, glucose, insulin, and ruminal temperature; and to describe the LM proteome and evaluate protein abundance in cows with different MR. Cows (4 to 7 yr of age) with a BCS of 5.0 ± 0.2 and BW of 582 ± 37 kg in the second to third trimester of gestation were studied in 3 trials (trial 1, n = 23; trial 2, n = 32; trial 3, n = 38). Cows were individually fed a complete diet in amounts to meet predicted MR (Level 1 Model of NRC), and feed intake was adjusted weekly until constant BW was achieved for at least 21 d (maintenance). Cows were classified on the basis of MR as low (>0.5 SD less than mean, LMR), moderate (±0.5 SD of mean, MMR), or high (>0.5 SD more than mean, HMR) MR. Blood samples were taken at maintenance and at 2 mo postpartum in trial 2. Muscle biopsies were taken from LMR and HMR after cows consumed actual MR for 28 d (trial 2) or 21 d (trial 3). Proteins from LM were separated by 2-dimensional difference gel electrophoresis and were identified, and abundance was quantified and compared. The greatest differences in MR between cows were 29%, 24%, and 25% in trials 1, 2, and 3, respectively. Daily MR (NEm, kcal·BW(-0.75)·d(-1)) averaged 89.2 ± 6.3, 93.0 ± 4.9, and 90.4 ± 4.6 in trials 1, 2, and 3, respectively. Postpartum BW and BCS, calf birth and weaning weights, postpartum luteal activity, and ruminal temperature were not influenced by MR of the cows. Concentrations of IGF-I were greater (P = 0.001) in plasma of MMR compared with LMR cows consuming predicted MR diets, and MR was negatively correlated with concentrations of IGF-I in plasma (r = -0.38; P = 0.05) at 2 mo postpartum. A total of 103 proteins were isolated from LM; 52 gene products were identified. Abundance of specific proteins in the LM was not influenced (P > 0.11) by MR. Variation in MR of cows will make it possible to improve feed efficiency by selection. Identification of biomarkers for MR will allow selection of more efficient cows, which consume less feed and produce calves with similar weaning weights. Productive cows that require less feed for maintenance will improve efficiency of production and enhance sustainability of the environment.

Genetic and genomic analysis of oxygen consumption in mice

“…In order to test this hypothesis, we performed selective signature detection analysis with pool‐seq data. Accumulating insight into genes relating to OC not only could contribute to develop an easier approach for estimating MER and RFI (e.g., Cantalapiedra‐Hijar et al, 2018; Cooper‐Prado et al, 2014; Gilbert et al, 2017), but also might give interesting information in terms of elucidating nuclear‐mitochondrial crosstalk (e.g., Cannino, Di Liegro, & Rinaldi, 2007; Liu et al, 2017; Poyton & McEwen, 1996).…”

Maintenance Energy Requirements of Double-Muscled Belgian Blue Beef Cows

“…It may be clear that a wide range of animal factors, such as genotype, and environmental factors can influence maintenance energy expenditure [ 32 ]. Even the technique to determine maintenance requirements is variable: zero BW change [ 30 , 35 , 36 , 37 , 38 , 44 ], zero energy retention [ 39 ], calorimetry chamber [ 40 ] or respiration chamber [ 41 ]. Furthermore, extra activity for walking may increase maintenance energy requirements.…”

Retained energy in lactating beef cows; effects on maintenance energy requirement and voluntary feed intake

“…Two experienced technicians recorded BCS, and these two scores were averaged within animal for each date. Daily feed allotment was adjusted by ≤0.45 kg DM if an individual’s BW fluctuated by ≥9 kg above or below initial (day 0) shrunk BW ( Cooper-Prado et al, 2014 ). Subsequent adjustments (≤0.45 kg DM) were made if weight change continued to increase or decrease ≥9 kg above or below initial study shrunk BW.…”