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United States Department of Agriculture

Agricultural Research Service

Title: Time of Calving: Economic and Biological Implications

Authors
item Short, Robert
item Grings, Elaine

Submitted to: Bovine Connection Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 1, 1999
Publication Date: December 1, 1999
Citation: SHORT, R., GRINGS, E.E. TIME OF CALVING: ECONOMIC AND BIOLOGICAL IMPLICATIONS. BOVINE CONNECTION PROCEEDINGS. 1999. p. 15-18.

Interpretive Summary: Decisions that result in optimum economic outcomes are complicated because of the hundreds of variables that must be taken into account that affect the economic and biological outcomes of the system, because these variables change dramatically over time (mainly seasonal and annual but at times the changes can be daily) and because the optimum integration of decisions is almost always regional and even site specific due to unique aspects of regional ecosystems and individual ranches or production systems. One of the most basic decisions that a cow/calf producer must deal with is when will cows be bred so calving occurs at the optimum time. In order to better understand the economic and biological variables associated with season of calving in a Northern Great Plains environment, we have initiated an experiment at Ft. Keogh to determine the effects of calving in Feb. (winter), April (spring) or June (summer). The spring calving group was included to represent the normal calving season for this area, the winter group was included to increase fall calf weights as is done currently in some systems and the summer calving group was included as a newer approach to more closely align nutrient peak requirements of the cow with that available from grazed forage in an attempt to decrease inputs from harvested forages and other feeds. In this region, range forage is highest in quality and quantity in June and is lowest in Jan. to March. Nutrient requirements of cows are highest about 30 days after calving and then decrease to the lowest point after weaning. The result of these 2 seasonal fluctuations is that the earlier a cow calves before June, the more out of synchrony her nutrient requirements are with available range forage.

Technical Abstract: Decisions that result in optimum economic outcomes are complicated because of the hundreds of variables that must be taken into account that affect the economic and biological outcomes of the system, because these variables change dramatically over time (mainly seasonal and annual but at times the changes can be daily) and because the optimum integration of decisions is almost always regional and even site specific due to unique aspects of regional ecosystems and individual ranches or production systems. One of the most basic decisions that a cow/calf producer must deal with is when will cows be bred so calving occurs at the optimum time. In order to better understand the economic and biological variables associated with season of calving in a Northern Great Plains environment, we have initiated an experiment at Ft. Keogh to determine the effects of calving in Feb. (winter), April (spring) or June (summer). The spring calving group was included to represent the normal calving season for this area, the winter group was included to increase fall calf weights as is done currently in some systems and the summer calving group was included as a newer approach to more closely align nutrient peak requirements of the cow with that available from grazed forage in an attempt to decrease inputs from harvested forages and other feeds. In this region, range forage is highest in quality and quantity in June and is lowest in Jan. to March. Nutrient requirements of cows are highest about 30 days after calving and then decrease to the lowest point after weaning. The result of these 2 seasonal fluctuations is that the earlier a cow calves before June, the more out of synchrony her nutrient requirements are with available range forage.

Last Modified: 7/23/2014
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