Impact of cow size on dry matter intake, residual feed intake, metabolic response, and cow performance

Abstract

Thirty-eight Angus-cross beef cows were used to evaluate differences in DMI, residual feed intake (RFI), and endocrine markers on the basis of cow size and RFI ranking during 2 stages of production. Cows housed in individual pens (2.2 × 9.1 m) were fed, over a 70-d feeding period, 30% Bermuda grass hay and 70% ryegrass baleage diet during lactation (LACT) and a 100% ryegrass hay diet during postweaning (NOLACT). Individual daily feed intake, BW, and BCS were recorded, and hip height was used to determine frame score (FS). Feed intake was used to calculate RFI for each cow, and cow was the experimental unit. Blood samples were obtained on d 0 and 70 and were analyzed for glucose, insulin, leptin, triiodothyronine (T3), and thyroxine (T4). Cows were assigned to a light (LIT) or heavy (HEV) BW groups on the basis of mean BW at the beginning of the LACT period. On the basis of RFI values for each feeding period, cows were placed into a negative (NEG; RFI < 0.00) or positive (POS; RFI > 0.00) RFI group and into a low (LOW; ≤0.2 SD mean RFI), medium (MED; within ±0.19 SD), or high (HI; ≥0.2 SD mean RFI) RFI group. During LACT, DMI was 4.8% greater (P = 0.03) and FS was greater (P < 0.01; 6.4 and 5.5 ± 0.16) for the HEV compared with LIT BW cows. No RFI by day interaction or RFI group main effect occurred for endocrine markers during LACT; however, a negative relationship (P = 0.04) existed between BW group and combined T3 data, and a positive relationship (P = 0.04) existed between RFI and combined insulin data. For both LACT and NOLACT, RFI was similar (P > 0.05) among BW groups; however, DMI was 6.5% and 8.9% greater (P < 0.01) for POS compared with NEG RFI in the LACT and NOLACT periods. In LACT, DMI was greater (P < 0.01) for HI and MED RFI compared with LOW RFI, and in NOLACT, DMI was greater (P < 0.01) for the HI compared with MED and LOW RFI cows and MED compared with LOW RFI cows. During NOLACT, DMI was 8.9% greater (P < 0.01) for the HEV (12.4 ± 0.22 kg) compared with LIT (11.3 ± 0.19 kg) BW cows. Change in BCS was greater (P ≤ 0.03) in higher RFI cows in both RFI groups only in the NOLACT period. Differences in T3 and T4 on d 0 and 70 were 25% and 15% greater (P ≤ 0.04) for the LIT BW group compared with the HEV BW group. A negative correlation existed (P ≤ 0.04) between BW group and T3 and T4, as well as leptin and RFI (P = 0.03). Although cow BW was independent of RFI and T3 and T4 levels tended to be greater in lighter BW cows, DMI was consistently greater for cows with heavier BW and higher RFIvalues.

Effects of residual feed intake and dam body weight on replacement heifer intake, efficiency, performance, and metabolic response

“…At weaning during the fall of 2011, all cows in the herd were sorted into a light (LIT; 488 ± 30 kg) or heavy (HEV; 573 ± 39 kg) cow BW group based on the average BW of the entire herd. Forty-five AIpregnant cows gave birth to lactating cows during the spring of 2012, with 38 heifer calves selected for in take and feed efficiency evaluation in 2012 (Walker et al, 2015). Beginning mean BW in March of 2012 for dams of heifers used in the current study in the LIT and HEV BW groups were 544 ± 21.3 kg and 621 ± 34.8 kg, respectively.…”

Drought Consequences for Cow-Calf Production in Wyoming: 2011—2014

“…19 In reality though, the authors are suggesting breeding for greater 'forage conversion efficiency' because that is the assumption used in modeling-a trait that is not necessarily correlated with cow size. 18,19 Higher temperatures and heat stress alone can reduce cattle production by reducing feed intake, feed efficiency, and causing mortality. 20 The provision of shade and water offers 17 y Assuming an average 500 lb weaned calf across all cow sizes and across the drought gradient.…”

Can We Predict Forage Nutritive Value With Weather Parameters?

“…11 This approach is also relevant to EPDs associated with feed intake and efficiency as a recent study has concluded that bigger Angus cows ate more (i.e., DMI was 4.8% higher) but their feed efficiency was not different (i.e., residual feed intake) than small cows. 18 Moreover, as of late 2015, two major breed associations had started to use a DMI EPD because of the recent genetic trends in the cattle industry that have produced cattle with greater dry matter/ nutrient requirements of which increasing body size is one of the characteristics driving that trend (see American Angus Association https://www.angus.org/AGI/GenomicEnhancedEPDs. pdf and American Hereford Association http://www.hereford.…”

“…19 In reality though, the authors are suggesting breeding for greater 'forage conversion efficiency' because that is the assumption used in modeling-a trait that is not necessarily correlated with cow size. 18,19 Higher temperatures and heat stress alone can reduce cattle production by reducing feed intake, feed efficiency, and causing mortality. 20 The provision of shade and water offers y Assuming an average 500 lb weaned calf across all cow sizes and across the drought gradient.…”