Energy source and ionophore supplementation effects on lamb growth, carcass characteristics, visceral organ mass, diet digestibility, and nitrogen metabolism
Fl. Fluharty et al., Energy source and ionophore supplementation effects on lamb growth, carcass characteristics, visceral organ mass, diet digestibility, and nitrogen metabolism, J ANIM SCI, 77(4), 1999, pp. 816-823
In Exp. 1, 72 Targhee lambs (initial BW 22.1 +/- .3 kg) were used to determ
ine the effects of energy source (alfalfa pasture vs limit-fed, all-concent
rate) and ionophore addition on performance, visceral organ mass, and carca
ss characteristics. There were no differences (P > .10) in ADG or gain/feed
due to ionophore supplementation. Lambs that grazed alfalfa had greater (P
< .05) liver, omasum, abomasum, small intestine, cecum, and large intestin
e weights than did lambs fed the concentrate diet. Lambs fed the concentrat
e diet had greater (P < .01) hot carcass weights, larger (P < .01) loin eye
areas, and greater (P < .001) dressing percentages than lambs that grazed
alfalfa. In Exp. 2, lambs offered the concentrate diet had greater (P < .00
1) DM and OM digestibilities than lambs offered alfalfa (89.5 and 91.1 vs 7
2.4 and 74.2%, respectively). Apparent and true N digestibilities were grea
ter (P < .001) for the concentrate diet than for alfalfa (90.9 and 101.7 vs
77.7 and 91.9%, respectively). Likewise, grams of N retained per day were
twice as great (P < .001) with the concentrate diet than with alfalfa (14.9
vs 6.0 g/ d). The greater visceral organ mass and resulting increases in e
nergy and protein requirements in lambs that grazed alfalfa were probably r
esponsible for the lesser hot carcass weight and dressing percentage compar
ed with lambs fed 100% concentrate.