Eating a high fiber diet during pregnancy increases intake and digestibility of a high fiber diet by offspring in cattle

Abstract

Experiences early in life influence preferences for the forages which animals eat as adults, but little is known about how such experiences affect forage intake and digestibility. We hypothesized that experience with high fiber (HF) diets in utero enables cattle to better utilize HF diets by enhancing intake and digestibility of HF diets. We exposed cows to either HF or low fiber (LF) diets from October 20 until parturition on March 15. The HF diet was primarily ammoniated wheat straw (AWS), while the LF diet was mainly grass hay (700g/kg orchardgrass and 300g/kg meadow bromegrass). The two diets were iso-net energy (NEm), isonitrogenous, and similar in mineral and vitamin contents, but they varied 10-fold in neutral detergent soluble carbohydrates. Following weaning, the 8mo old calves from mothers fed HF or LF diets during pregnancy were fed AWS and a high fiber supplement, and dry matter (DM) intake and digestibility were measured during the last half of a 40d experiment (i.e., 26d adaptation, 14d measured DM intake, 5d measured DM digestibility). Intake (5.6 versus 5.3kg/d; P=0.04) and digestibility (545 versus 523g/kg; P=0.03) of AWS were higher for calves fed HF than for those fed LF diets. As a result, digestible DM intake of AWS was higher for HF than LF (3.1 versus 2.8kg/d; P<0.01). Calves fed HF diets ate more straw as a proportion of their diet than did calves fed LF (733 versus 723g/kg; P=0.05). Total digestible DM intake (i.e., AWS+supplement) was higher for calves fed HF than LF diets (4.7 versus 4.4kg/d; P<0.01), as was total diet DM digestibility (613 versus 600g/kg; P=0.07). Calves were weighed at the conclusion of the DM intake and digestibility measurement periods, and then fed an AWS/processed wheat middlings diet for an addition 28d to determine daily gain. Collectively, increases in intake and digestibility affected body weight gains such that HF diet fed calves numerically gained more than LF fed calves even during this short period (0.45 versus 0.41kg/d; P=0.13). Higher DDM intake is likely important for pregnant cows and their offspring which winter for many months under extensive range conditions on dormant forages where their NEm requirements are marginally satisfied. These effects on offspring, further magnified by experiences with their mothers early in life, make cows and their progeny better adapted to using dormant forages during winter.