Effect of Supplementary Feeding of Concentrates and of Restricted Grazing on Holstein Heifers on Intensively Managed Grasspastures

Abstract

Holstein heifers grazing unrestrictedly at 9 head/ha on steep, intensively managed grass pastures in the humid mountain region, and receiving no concentrate feed, gained 0.59 kg/head daily over a 240 day period. Heifers which received an additional 2.3 kg/head/day of concentrates gained 0.69 kg/head/day, and carrying capacity of the pastures was increased to 12 head/ha. Heifers grazing for only 8 hours/day, and fed 3.6 kg/head/day of concentrates gained 0.75 kg/head/day and carrying capacity of the pastures was increased to 15 head/ha. It was not economically beneficial to increase weight gains or carrying capacity of the pastures by feeding concentrates or by restricting grazing. In a 360-day experiment, during a 90-day period between all-grass rations, heifers ted only on pasture gained 0.58 kg/head/day and those that grazed for 6 hours/day and were fed 2.3 kg/head/day of concentrates made similar gains averaging 0.53 kg/head/day. However, heifers removed from the pastures during this period and fed 6 kg of bulky feed/head/day gained only 0.23 kg/head/day. When all three groups were returned to a full grass ration, those previously fed only on grass averaged 0.46 kg/head/day; those fed on bulky feed during the previous 90 days gained at a similar rate of 0.41 kg/ head/day, but those previously on restricted grazing plus concentrates gained only 0.32 kg/head/day. Overall average gains for the 360-day period were 0.54, 0.43 and 0.49 kg/head/day for these three feeding regimes, respectively. It was more economically beneficial to feed concentrates and to restrict grazing than to put the heifers on a full ration of bulky feed during periods of forage scarcity.