Effects of heat-stress on production in dairy cattle.

Invited review: production and digestion of supplemented dairy cows on pasture.

It is well documented that the stress of hot environments lowers productive and reproductive efficiency, in farm animals. Likewise, research information is available to aid in the management of livestock in such adverse conditions. However, practical methods to achieve the desired levels of productive and reproductive performance are lacking. Summer forages that will support a high level of productivity in subtropic and tropic regions are needed for ruminants. More critical information is needed on the total dietary needs of all farm animals in hot environments. Dietary emphasis should be to increase intake or to alter levels of proteins, amino acids or other nutrients to improve the conversion of feed units into production units. Increasing nutrient intake to support a higher level of production will render animals more sensitive, in terms of productive efficiency, to environmental modifications that improve comfort. This should be especially pertinent in the humid Southeast and other regions where production responses to environmental modifications have been variable. There is limited information on the effect of the night cooling cycle on productive efficiency and on the effect of severe heat stress on reproductive phenomena not related to conception.

Heat stress as it affects animal production.

Rabbits’ productive, reproductive and physiological performance traits as affected by heat stress: a review

Environmental stressors are involved in the etiology of important livestock diseases, including transmissible gastroenteritis in young pigs, Newcastle's and Marek's disease in chickens and shipping fever in cattle. Unfortunately, very little research has been conducted to learn how stress alters host resistance, although it is generally assumed that the immune system of the host is affected. This paper identifies eight stressors that typically occur in modern livestock production units: heat, cold, crowding, mixing, weaning, limit-feeding, noise and restraint. All of these stressors have been shown to alter the immune system of animals. These changes in immune function may ultimately explain the physiological basis of disease-environment interactions. A thorough understanding of stress-induced changes in host resistance will also provide the scientific basis for effective prophylactic therapy. More controlled experiments are needed to learn how stress alters the susceptibility of animals to infectious and noninfectious diseases.

Stress and immune function: a bibliographic review.

Effect of temperature-season on bovine adrenal cortical function, blood cell profile, and milk production.

Crude protein and rumen undegradable protein effects on reproduction and lactation performance of Holstein cows

Effect of Zone Cooling on Milk Yield, Thyroid Activity and Stress Indicators

Early-season forage production of annual ryegrass (Lolium multiflorum Lam.) is reduced in the southeastern USA when established no-till rather than with conventional tillage. We hypothesized that annual warm-season grass residue interferes with seedling establishment under no-till. In a two-year study, we evaluated six strategies for managing residue from warm-season annual grass on annual ryegrass establishment, forage production, and soil moisture. Treatments were (i) no herbicide, mow, and leave residue; (ii) tillage 30 and 7 d before planting ; (iii) apply glyphosate [isopropylamine salt of N-(phosphonomethyl)glycine] 30 d before planting, mow, and leave residue; (iv) apply glyphosate 7 d before planting, mow, and leave residue; (v) apply glyphosate 7 d before planting, apply additional residue from twice the plot area (i.e., three times the other residue treatments); and (vi) apply glyphosate 7 d before planting, burn residue 1 d before planting. Better stands and more forage production at first harvest of annual ryegrass were obtained by spraying and burning residue (two-year average of 96% stand and 0.92 Mg ha -1 yield at the first harvest) or spraying 30 d before planting (92% stand. 0.92 Mg ha 1 ) than when annual ryegrass was planted into a 3 x residue (55% stand, 0.24 Mg ha '). Soil moisture at planting did not cause differences in stand establishment among treatments. We conclude that managing residue during no-till establishment by controlling warm-season annual grasses and burning or controlling warm-season annual grasses 30 d before planting can improve stands and forage production of annual ryegrass.

J. F. Beatty

Papers

Effect of temperature-season on bovine adrenal cortical function, blood cell profile, and milk production.

Crude protein and rumen undegradable protein effects on reproduction and lactation performance of Holstein cows

Effect of Zone Cooling on Milk Yield, Thyroid Activity and Stress Indicators

Management of warm-season annual grass residue on annual ryegrass establishment and production

Influence of Zone Cooling on Performance of Cows Lactating During Stressful Summer Conditions