Effect of mature body weight and stocking rate on cow and calf performance, cow herd efficiency, and economics in the southeastern United States1

Abstract

Eight 4-ha mixed warm-season grass pastures in southwestern Arkansas (33°40'4″ N, 93°35'24″ W, and elevation 107 m) were stocked with either large mature size (571 kg [SD 55.2] BW) or small mature size (463 kg [SD 58.2] BW) spring-calving cows at 4 stocking rates (SR; 1, 1.5, 2, or 2.5 cow-calf pairs/ha) over 4 yr to test the effects of SR and mature body size on cow and calf performance and system economics. Each pasture received 112 kg/ha N as ammonium nitrate in May and was broadcast seeded to annual ryegrass ( Lam.) in mid October each fall along with 112 kg/ha N as ammonium nitrate. Data were analyzed by regression to determine the effects of cow size and SR on calf performance, cow BW change, calf gain, weaning weight per hectare, hay feeding requirements, and net returns. As SR increased, cow BW and BCS at weaning decreased ( < 0.01) by 26 kg and 0.36 condition scores, respectively, for each additional cow stocked per hectare ( = 0.44). Calf BW at weaning in October increased ( < 0.01) 19 kg for each 100-kg increase in cow BW but was not affected ( = 0.66) by SR. As cow BW increased, calf BW at weaning per 100 kg cow BW decreased ( < 0.01) 6.7 kg for each 100-kg increase in cow BW but was not affected ( = 0.44) by SR. Neither cow BW nor SR affected ( ≥ 0.53) pregnancy percentage, which averaged 88% over the 4-yr experiment. Calf BW weaned per hectare was not affected ( = 0.75) by cow BW but linearly increased ( < 0.01) by 217 kg for each additional cow per hectare SR. Hay feeding days and cost of hay per cow increased ( ≤ 0.05) and kilograms of hay offered per cow tended ( = 0.09) to linearly increase with increasing SR, yet cow BW had no effects ( > 0.22). Although there were no effects ( ≥ 0.38) of cow BW on carrying cost or net returns, increasing SR decreased ( < 0.01) total expenses by US$102/cow and increased net returns by $70/cow and $438/ha for each cow per hectare increase in SR. These data indicate that increasing cow size can increase weaning BW of calves but does not affect total production per hectare or profitability, even though weaning weight efficiency ratios were reduced. Increasing SR reduced cow BW and BCS at weaning and increased feeding of conserved forages but did not affect pregnancy rates and led to increases in total calf BW weaned per hectare and net returns.

Effects of stocking rate, forage management, and grazing management on performance and economics of cow–calf production in Southwest Arkansas1

“…Net return per hectare of HR ($1,025 ± 63.0/ha) was greater (P < 0.01) than that of MR ($479 ± 63.0/ha), which was numerically greater than that of CG ($429 ± 63.0/ha). The relationship between costs on a per-hectare and per-cow basis to the increased SR of HR in the current experiment are similar to those reported by Beck et al (2016), who reported that as SR increased, total cost per hectare increased but total cost per cow decreased. Beck et al (2016) likewise found that as SR increased, net return per hectare increased, but in contrast to the current research, net return per cow also increased with increasing SR. Wyatt et al (2013a) found that labor costs per cow decreased with increasing SR, along with increasing total sales revenue and return over total expenses.…”

“…Cow BCS were above the BCS that would impact reproductive performance of the cows (Selk et al, 1988), and therefore, cow BCS was not likely a factor in reproductive success among pasture management system. Similar to the current research, Beck et al (2016) reported that pregnancy rates were not affected by increasing SR of cows from 1 to 2.5 cows/ha even though BCS were reduced by 0.36 units for each 1 cow/ha increase in SR.…”

“…The decrease in forage mass and improvement in nutritive quality (increased CP and TDN and decreased NDF and ADF) in HR compared with MR and CG in the late summer is similar to changes with increasing SR observed by Beck et al (2016). Also similar to the current research, Wyatt et al (2012a) found that forage CP and in vitro digestibility were less in rotationally grazed pastures stocked at a moderate SR compared with pastures managed with continuous grazing stocked at a moderate SR or rotationally grazed pastures stocked at a high SR.…”

“…The reduction in cow BW and calf performance with increased SR was expected, as reduced animal performance is a common response to increased SR in a variety of environments (Bagley et al, 1987;Gillen and Sims, 2002;Wyatt et al, 2012bWyatt et al, , 2013bBeck et al, 2016). Similar to the results of the current research, increasing SR has been shown to lead to increased calf BW weaned per hectare (Bagley et al, 1987;Gillen and Sims, 2002;Wyatt et al, 2012bWyatt et al, , 2013bBeck et al, 2016). Bagley et al (1987) reported that weaning weight per hectare increased 22% when SR increased from 2.9 to 3.8 cows/ha, even though BW weaned per cow decreased by 12 kg.…”

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

“…For example, a recent study on fertilized small pastures (~8 ac) in southwestern Arkansas showed larger cows (1,258 lb) did wean~45 lb heavier calves than small cows (1,020 lb). 15 Contradictory results from a semi-arid rangeland environment in Wyoming recently indicated however that smaller cows weaned calves as heavy as the largest cows and may have an advantage over large cows due to their ability to reduce forage inputs while simultaneously increasing total output measured in annual total weaned weight of calves. 16 Using this general result for the cow size*rangeland environment interaction, we developed a hypothetical modeling scenario presented in Table 1 that we suggest for western rangelands.…”