The relationship of forage intake, residual feed intake, and greenhouse gas emissions between lactation and gestation in beef cows

Unofficial AI-generated summary based on the public title and abstract. Not an official translation.

🔬研究者:Provides data on RFI stability and methane emissions across physiological stages in beef cows.

🏢実務担当者:Can inform selection of feed-efficient cows to reduce feed costs and methane emissions.

Abstract The objective of this research was to evaluate dry matter intake (DMI), residual feed intake (RFI), and greenhouse gas emissions between lactation and gestation in mature beef cows fed an unprocessed grass hay diet. A two-year experiment was conducted using 67 mature Angus and Angus-cross cows (n = 41, Year 1; n = 26, Year 2) which included a minimum 85-d early-mid lactation trial (LACT) followed by a minimum 85-d early-mid gestation trial (GEST) in both years. Cows were housed in drylot pens at the Oklahoma State University Range Cow Research Center. Each pen was equipped with an individual intake monitoring system (SmartFeed, C-Lock Inc., Rapid City, SD) with a stocking density of 2.7 cows per feeder in Year 1, and 2.9 cows per feeder in Year 2. Cows were offered ad libitum access to long-stem, unprocessed bermudagrass hay (≥12.6% CP and ≥ 57% TDN, LACT; ≥12.4% CP and ≥ 54% TDN, GEST) and a mineral supplement. An open-circuit, portable gas quantification system (GreenFeed, C-Lock Inc., Rapid City, SD) was placed in pens to measure carbon dioxide (CO2), methane (CH4), and oxygen (O2) flux. Cows were classified by K-means clustering into three categories of feed efficiency based on RFI of efficient (n = 23, LACT; n = 23, GEST), moderate (n = 27, LACT; n = 25, GEST), and inefficient (n = 17, LACT; n = 16, GEST) classifications. Efficient, moderate, and inefficient LACT DMI means were 13.9, 15.1, and 16.8 kg/d, and GEST DMI means for the 3 groups were 11.5, 12.6, and 15.2 kg/d respectively (P < 0.001). Efficient classified cows consumed 18.8% (LACT) and 27.8% (GEST) less hay than inefficient classified cows (P < 0.001). There were no differences for body weight (BW), average daily gain (ADG), milk yield, body condition score (BCS), or calf weaning weight (WW) between classification groups in either physiological stage (P ≥ 0.52). There were strong (P < 0.001) positive phenotypic correlations for DMI (r = 0.82) and RFI (r = 0.68) between LACT and GEST. There were positive phenotypic correlations (P < 0.001) between DMI and CO2, CH4, or heat production (HP) during LACT (r = 0.70 CO2; r = 0.61 CH4; r = 0.65 HP) and GEST (r = 0.58 CO2; r = 0.52 CH4; r = 0.58 HP). The results from this study suggest that identifying feed efficient mature cows based on RFI results in lower DMI with no difference in output metrics, and that RFI remains constant across physiological stages.

• crossref https://doi.org/10.1093/tas/txag071first seen 2026-05-29 06:18:32 · last seen 2026-06-11 05:18:11