Early-vegetative tall fescue hay vs alfalfa hay as a supplement for cattle consuming low-quality roughages

Two studies were conducted to evaluate high-quality tall fescue hay as a supplement to beef cattle fed low-quality roughages. In Exp. 1, 15 ruminally cannulated Hereford x Angus steers (average weight 390 kg) were blocked by weight and assigned randomly to one of three treatments: 1) tall fescue straw, no supplement; 2) tall fescue straw plus tall fescue hay supplement; 3) tall fescue straw plus alfalfa hay supplement. The 28-d digestion study consisted of 14 d of adaption, 6 d of intake data, and 6 d of collection of feces, respectively, with a 1-d ruminal sampling (d 27) and ruminal evacuations (d 28). In Exp. 2, 90 gestating Hereford x Angus cows were stratified by age and body condition and, within stratum, assigned randomly to three replications of the same treatments as described for Exp. 1. In both studies, a basal diet of tall fescue straw was fed with ad libitum access, alfalfa hay was fed at .4% BW, and tall fescue hay was fed at a level isonitrogenous with the alfalfa hay (.61% BW). In Exp. 1, DMI was at least 13% greater (P < .01) for supplemented steers than for nonsupplemented steers and was 12% greater (P < .10) for steers receiving supplemental tall fescue hay than for alfalfa hay-supplemented steers. Digestibility of DM was greater for supplemented steers than for nonsupplemented steers (P < .05) and, between supplement treatments, greater for tall fescue hay-supplemented steers than for alfalfa hay-supplemented steers (P < .10). Ruminal ammonia values peaked at 3 h after feeding and were higher for steers fed supplement treatments than for those fed the control treatment from just before feeding through 6 h after feeding (P < .10). In Exp. 2, supplemented cows gained more BW than nonsupplemented cows (P < .01), and the tall fescue hay-supplemented cows gained more BW (P < .10) than cows supplemented with alfalfa hay. Likewise, supplemented cows lost less condition (P < .01) than their nonsupplemented counterparts during the 84-d supplementation period, and cows receiving tall fescue hay supplement tended (P = .23) to lose less condition than cows receiving alfalfa hay supplement. No differences in calf growth were noted among treatment groups (P < .10). In conclusion, supplementation of high-quality tall fescue hay to cows fed low-quality forage diets seems to result in performance that is similar to or better than that of cows receiving alfalfa hay supplements when fed on an isonitrogenous basis.