Live-Weight Gains of Pasture-Fed Dairy Heifers

It is well known that size of cow bears a close relation to milk-producing capacity.Large size is best obtained through programs of feeding and management which will produce rapid live-weight gains throughout the developmental period prior to first calving.While pasture feeding is one of the best ways of inducing good growth in heifers, pasture forage yields vary greatly from farm to farm, depending upon kind of pasture crop and fertility of the s0il, and from month to month, or season to season, depending upon rainfall and temperature.The live-weight gains of heifers having access to pasture as the only feed are likely to follow the same trends as the pasture forage yields and may be positive or negative.How much live-weight gain do dairy heifers make when pasture is the only source of feed ?Do the dairy breeds differ in their ability to utilize pasture for growth ?But few reports" of experiments which supply answers to these questions are to be found in the literature.Bender and Bartlett (1) observed losses in weight of 40 to 100 pounds per head during the first month after fat two-year-old heifers were turned to pasture, while heifers winter-fed on roughage suffered no loss in weight and made greater total gains for the season.Eckles (2) made comparisons of the efficiency of Holstein and of Jersey heifers in the use of alfalfa hay only and a combination of alfalfa hay and corn silage for the making of winter live-weight gains.The Holsteins consumed more feed, made larger daily gains, and required less feed per pound of gain.Hayden (3) found that 29 Jersey heifers, one to two years of age, which were kept at pasture for 159 days, made daily gains for the year equivalent to 0.8 pound per head ; while 22 Holstein heifers of the same age, which were pastured 151 days, made daily gains during the year amounting to 1.0 pound per head.Henderson and Anthony (4) reported daily live-weight gains of yearling dairy heifers kept at pasture from 194 to 203 days as ranging from 0.3 to 1.13 pounds per head.In a farm survey conducted by 1V[isner (5), it was found that the gain in weight of heifers in 107 dairy herds, the majority of which were grade Holstein, amounted to 261 pounds during the period from 12 to 24 months of age.The heifers were pastured for approximately 169 days. EXPERIMENTAL PROCEDUREThe records of 178 dairy heifers which had access to pastures, water, and salt as the only sources of feed during approximately five months of the year form the basis of the present study.The records covered the years 1936 to