Drylot vs Pasture: Early-Weaned Lamb Performance to Two Slaughter Weights

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Abstract
Seventy-two early-weaned lambs were randomly allotted to four management systems: (1) PNC = bluegrass-clover pasture with no supplemental concentrate; (2) PI 3 = bluegrass-clover pasture with a 13% crude protein (CP) supplemental concentrate offered ad libitum;(3) DL13 = 13% CP diet offered ad libitum in drylot; and (4) DL16 = 16% diet offered ad libitum in drylot. Average daily gains for PNC lambs were lower (P<.01) than the mean of P13, DL13 and DL16. P13 lambs had similar gains to DL13 and DL16 lambs while consuming 48% less concentrate, indicating the effectiveness of dietary forage in contributing to live-weight gain. Lambs in the PI3 system were the most efficient (P<.01) converters of concentrate to gain. Daily carcass crude protein (P<.1) and carcass ether extract gains (P<.01) were lower in the PNC lambs. P13 lambs tended to gain less crude protein daily while ether extract daily gain was lower (P<.01) than the mean of DL13 and DL16. Efficiency of protein gain was highest (P<.05) in P13 lambs, while feed required per unit of ether extract gain did not differ among P13, DL13 and DL16 management systems. The lowest (P<.01) dressing percentages and quality grades (P<.01) were found in PNC lambs. Yield grade of PNC carcasses was highest (P<.01), while P13 carcasses had higher (P<.01) yield grades than drylot lambs. Lambs slaughtered at the 40.8 kg slaughter weight were more efficient (P<.1) in feed conversion compared to 49.9 kg. Lambs slaughtered at 49.9 kg had higher (P<.01) dressing percentages, higher (P<.01) quality grades and lower (P<.01) yield grades than lambs slaughtered at 40.8 kilograms. These data indicate use of a pasture plus supplemental concentrate management system may be warranted by production of a lean carcass with sufficient fatness to result in commendable quality. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.