Cow Efficiency & Forage Intake Research at the OSU Range Cow Research Center

Paul Beck, Oklahoma State University State Extension Beef Nutrition Specialist

Growth rates and carcass weights have been increasing over the last 30 years. However, little research has been conducted to determine how aggressive selection for production traits affects beef cow maintenance requirements.

It is thought that cows with greater genetic capacity for growth, milk and mature weight have greater maintenance energy requirements. To measure this, Amanda Holder, a graduate student at the OSU Range Cow Research Center examined the effects of diet type on greenhouse gas emissions and dry matter intake estimation.

They used 42 Angus cows with a wide range in DMI EPD (-1.36 to 2.29) and were fed either grass hay only or a mixed diet of 35 percent hay and 65 percent concentrate feeds. They found that intake of the mixed ration and the long-stem hay were correlated, but cow weight gain while consuming hay was not correlated with cow weight gain while consuming the concentrate-based diet.

As intake of both diets increased, both CO 2 and methane production increased. Daily greenhouse gas emissions increased with increasing feed intake and were lower when cows consumed hay compared to emissions during the period cows consumed the mixed diet.

A study by OSU graduate student Emma Briggs investigated hay voluntary intake and its relationship to both recovered energy (cow weight gain and milk production) and