Pellet and block supplements for grazing ewes

Pregnant Targhee ewes (N=120; 2–6 years of age) grazing native winter range were used to determine the effects of a 25% CP (as-fed) supplement provided in pellet (P) or block (B) form on supplement and forage intake and bodyweight change. Ewes receiving P were group-fed 6.82 kg per day of a wheat middling-soybean meal based pellet in troughs. Block fed ewes had ad libitum access to a cooked molasses based block. The study was conducted for 41 days in southwestern Montana (USA) starting 1 December 1999. Supplement treatments were crossed over upland (U) and lowland (L) pastures on day 21. Supplement DMI was greater (P=0.001) for P than B supplemented ewes with a coefficient of variation of 32 and 99.5%, respectively. The proportion of ewes consuming less than 20% of mean supplement DMI was 2 and 35% for P and B ewes, respectively. Two-year-old P ewes consumed less (P<0.05) supplement than all older P ewes and 2- and 3-year-old B ewes consumed less (P<0.05) supplement than 5- and 6-year-old ewes. Supplement treatment×pasture interactions were detected (P<0.001) for forage DMI and bodyweight change. Forage DMI and bodyweight change were greatest (P<0.01) by LP ewes, intermediate (P<0.01) for UB and LB ewes, and lowest (P<0.01) by UP ewes. Delivery method affected individual animal consumption of supplement and younger ewes consumed less supplement. Pasture conditions and consequently forage DMI had a greater impact on bodyweight change than supplement DMI or delivery method. Achieving planned individual ewe supplement intake appears to be best accomplished using a limit-fed pelleted supplement rather than allowing grazing ewes ad libitum access to a molasses based block supplement.