|Calves fed ammoniated wheat straw (AWS) with their mothers during the first 3 months of life perform better on AWS as adults. Does AWS in the diet of pregnant cows affect the intake and digestibility of AWS by their calves?
Cows were fed a either a high-fiber diet (HF) of ammoniated wheat straw (AWS) and wheat middlings (WM) or a low-fiber diet (LF) of grass hay and barley. Both diets contained the same amount of net energy, nitrogen, minerals and vitamins, but they varied 10-fold in the solubility of carbohydrates in the diet.
Cows were fed either HF or LF during the last 5 months of pregnancy. At calving, all cow-calf pairs were fed high quality alfalfa-grass hay for 45 d then moved to pasture for 5 months. Calves were weaned at seven months and fed good quality alfalfa hay 3weeks.
For 40 days, all calves were fed WM supplement and AWS ad libitum. Calves from cows fed HF during pregnancy ate more AWS, and it was more digestible compared to calves from cows fed LF diets. There was also a tendency for calves fed AWS + WM to gain more weight if their mothers had eaten HF rather then LF.
Higher digestible intake of poor quality forage is likely important for pregnant cows that winter on rangelands. Cows eating high-fiber diets during pregnancy and after calving likely produce replacement heifers that will be more productive on poor-quality forages during winter.
Ref: Wiedmeier, RD, JJ Villalba, A Summers and FD Provenza. 2012. Eating a high fiber diet during pregnancy increases intake and digestibility of a high fiber diet by offspring in cattle. Anim. Feed Sci. Tech. 177:144-151.