Summer Feeding of Dairy Cattle. A Review

Abstract

Income for dairy farmers during the summer depends to a considerable extent on more pasture herbage production in hot-dry weather. The results of recent studies indicate that dairy cattle fed an adequate ration, and allowed to graze nights and days with shade during the days, are far less affected by high environmental temperatures than previously supposed. Increased quality and quantity of forage may be enhanced by: (a) growing crops more resistant to heat and drought, (b) maintaining more moisture in the soil by less defoliation of plants which give shade to the soil, (c) irrigation, and (d) fertilization of the soil (especially with nitrogen, phosphorus, and potassium). The problems involved in using animal production (growth, milk yields) in pasture evaluation were pointed out. Indirect methods of pasture evaluation using internal and external indicators were described. A combination of internal and external indicators makes possible the estimation not only of the chemical composition but also of the coefficient of digestibility and dry matter intake of pasture. Dry matter intake from pasture is variable, but usually is about 30 to 35 lb. per day for cows weighing 1,200 lb. Grazed pasture herbage is higher in crude protein and lower in crude fiber and higher in digestibility than comparable hand-fed herbage. The requirements of grazing cattle are about the same as in barn-feeding, with the exception of digestible energy. Grazing cattle require from 1 to 3 lb. of TDN per cow per day more than those barn-feeding. Losses of pasture herbage from trampling, when properly managed, are about 10 to 15%. These losses are much higher with tall pastures. Temporary pastures, such as Sudan grass, are needed in many areas to supplement perennial pastures during the summer. The success of different systems of pasture utilization hinges on proper management (proper stocking rate, use of high-producing cows). Rotational and strip-grassing systems aid in using intensive pastures. Soilage may be used to advantage on farms where good pasture land is not conveniently located. Where soilage and stored feed may be used to advantage was pointed out. The fermentation vat of calves fed feeds other than milk alone is sufficiently developed at 2 to 4 mo. of age to handle good pasture, but the calves will starve on poor pasture. Certain pasture forages, such as Sudan grass, may contain considerable hydrocyanic acid. When properly managed, however, the danger from prussic acid poisoning is not great. Although the cause of pasture bloat is not known, recent results indicate that the administration of penicillin prevents bloat for a short time. Also, vegetable oils sprayed on “bloaty” pastures, added to the drinking water or to the feed, reduce the incidence of bloat. Milk produced by cows on pasture is more resistant to oxidized flavor than when winter feeds are fed. Pasture feed flavors may be avoided by removing cows from pasture 3 to 5 hr. prior to milking. © 1959, American Dairy Science Association. All rights reserved.