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Title: Bermudagrass intake and efficiency of utilization in Katahdin, Suffolk, and reciprocal-cross lambs

item Brown, Michael
item Starks, Patrick
item GAO, F - Grassland Research Institute
item WANG, X - Xinjiang Agricultural University
item WU, J - Gansu Agricultural Uiversity

Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2011
Publication Date: 6/15/2012
Citation: Brown, M.A., Starks, P.J., Gao, F.Q., Wang, X.Z., Wu, J.P. 2012. Bermudagrass intake and efficiency of utilization in Katahdin, Suffolk, and reciprocal-cross lambs. Professional Animal Scientist. 28:358-363.

Interpretive Summary: With increased demands for feed grains there is greater need to utilize forages in grazing animals to produce weight gains. While forage quality generally meets nutritional needs of growing animals early in the grazing season, forage quality rapidly declines and nutritional deficiencies can occur and supplementation of livestock is necessary to produce body weight gains consistent with the genetic potential of the animals. However, estimates of forage intake along with forage quality estimates are necessary to precisely determine deficiencies. Research at the Grazinglands Research Laboratory estimating intake on stocker lambs of hair sheep, wool sheep and their crosses has indicated an advantage in both intake and efficiency of forage utilization in lambs from hair sheep ewes. Additionally, results from this research suggest that measures of both forage digestibility and forage fiber content are useful in predicting intake from forage quality. Consequently, it may be possible to develop more efficient grazing systems through appropriate use of breed resources and precision supplementation may be possible through prediction of intake from forage quality.

Technical Abstract: Daily intake of fresh common bermudagrass was estimated using 12 spring-born Katahdin, Suffolk, and reciprocal-cross ewe lambs (n=3 per breed group) individually fed fresh harvested forage in pens in each of three years. Two 24-h estimates of intake were measured for each week of the study from June to August in each year. Intakes were expressed as both daily DM offered minus DM refused and daily as-fed forage offered minus as-fed forage refused. Efficiency of forage utilization was estimated similarly as kg DM intake per kg gain and kg as-fed intake per kg gain. Averaged over the two days per week and weeks of the study, DM intake as a percent of body weight averaged 2.92%, 2.57%, 3.05%, and 2.60% in Katahdin, Katahdin x Suffolk, Suffolk x Katahdin, and Suffolk, respectively (sire breed listed first). Intake was highest in the Suffolk x Katahdin and Katahdin ewe lambs (P < 0.05) compared to Katahdin x Suffolk and Suffolk lambs. There was little evidence for direct heterosis or direct breed effects for DM intake as a percent of BW, but there was evidence of maternal breed effects in favor of Katahdin ewes (0.48 kg/kg BW, P < 0.01). Efficiency of forage utilization averaged 4.26, 5.19, 4.47, and 5.30 kg DM per kg gain for Katahdin, Katahdin x Suffolk, Suffolk x Katahdin, and Suffolk, respectively. Efficiency was more favorable in lambs from Katahdin ewes compared to lambs from Suffolk ewes ( P < 0.07). These results indicate that genetic effects associated with breed can play an important role in regulating intake and efficiency in grazing animals and that breed composition should be considered in the design of efficient grazing systems.