A Comparison of Zero, Moderate, and Liberal Levels of Grain Feeding for Lactating Cows on Permanent, Improved, and Supplemental Pasture

SUMMAI~¥Two grsin-feeding trials, involving the continuous employment of 2t and 18 lactating dairy cows, were conducted during the 1956 and 1957 pasture seasons.Three types of pasture were utilized in each of the two seasons.The feeding of a moderate (5-6 lb.) or a liberal (10-12 lb.) amount of grain had no significant effect on milk production or on body weight.Grain feeding caused a reduction in the consumption of pasture dry matter of 1.8-3.8 and 3.0-7.5 lb. at the moderate and liberal rates of grain feeding.The net ga.ins in total dry matter consumption were 1.3 and 1..1 lb. for the moderate and liberal grain levels in 1956.In 1957, these values were 2.4 and 5.5 lb., respectively.The different response from grain feeding in the two seasons likely was due to a lower-quality pasture in 1957.In both trials, there was a highly significant difference in average dry matter digestibility among pastures in favor of orchardgrass-Ladino clover and orchardgrass-Ladino (-lover plus Sudan grass over Kentucky bluegrass-white clover pasture.Protein digestibility was greater during the 1956 pasture season, probably as a result of the greater and more even distribution of rainfall.Efforts to minimize the summer slump in milk production largely have been concerned with methods of maintaining a high nutrient intake.Seath and Miller (13) reported a considerable reduction in the grazing time of cattle during hot weather.This finding suggested a need for supplying additional feedstuffs to compensate for what may have been a decreased pasture consumption.Supplemental feeding of hay or silage to cows on good pasture has been ~hown by Seath et al. (I0, 11,12) and Cole et al. (3) to have little effect on milk production or body weight.The ingestion of supplemental feectstuffs apparently was accompanied by a corresponding reduction in forage intake.Traditionally, grain feeding has been considered as a means of filling the gap between a cow's total energy requirement and the amount of energy the animal can obtain from roughages.Previous work (4,6,7, 8) has shown little benefit from grain feeding, but few data are available to indicate the reason for this lack of response.Because of the inadequacy of experimental data relating to the supplementation of summer pastures with varying amounts of grain, this experiment was undertaken to' measure the influence of grain feeding on forage dry matter intake and digestibility, protein digestibility, total dry matter intake, milk production, and body weight of grazing, lactating dairy cows. EXPERIMENTAL PROCEDUREThis experiment was conducted during the ]956 (Trial 1) and the 1957 (Trial 2) pasture seasons.The trials lasted 16 and 20 wk., respectively.Trial 2