Prepartum dietary energy source fed to beef cows: II. Effects on progeny postnatal growth, glucose tolerance, and carcass composition

RADUNZ A.E.; FLUHARTY F.L.; A. E. RELLING,; FELIX T.; SHOUP L.; ZERBY H.N.; LOERCH S.C.

JOURNAL OF ANIMAL SCIENCE

AMER SOC ANIMAL SCIENCE

Lugar: Urbana; Año: 2012

0021-8812

Mature Angus-cross beef cows (n = 231) were used to evaluate effects of prepartum dietary energy source on postnatal growth and carcass composition of progeny in a 2 yr study.  Starting at approximately 160 d of gestation, cows were fed diets consisting of 1 of 3 primary energy sources at isocaloric intakes: grass hay (HY), corn (CN), or dried corn distillers grains (DG). Following parturition, cows were fed a common diet, and managed as 1 group.  Calves were weaned at an average of 185 ¡À 6 d of age, and backgrounded for 28 d.   A subset of progeny (n = 134) was individually fed a common finishing diet until slaughter, when each calf reached 1.2 ¡À 0.05 cm of backfat.  A glucose tolerance test (GTT) was conducted in year 2 on 4 calves/treatment after 41 and 111 d on the finishing diet (DOF).  Calf birth weights were greater (P = 0.002) in calves from cows fed CN and DG than calves from cows fed HY, and weaning BW (P = 0.08) was lighter for calves from cows fed HY vs. CN.  Receiving BW, final BW, and HCW were similar (P ¡Ý 0.16) among treatments.  No difference (P ¡Ý 0.28) in ADG, morbidity, and mortality from birth to slaughter was observed among treatments.  In response to a GTT, increased DOF resulted in greater (P ¡Ü 0.005) fasting insulin, faster glucose disappearance rate, and greater insulin:glucose area under the curve ratio. Glucose disappearance rate was greater (P = 0.01) in calves from cows fed CN than calves from cows fed HY or DG. A greater initial insulin response (P = 0.005) was observed in calves from cows fed CN or DG than calves fed HY. Carcass traits used to measure yield grade were similar (P ¡Ý 0.19) among treatments.  Calves from dams fed CN had the lowest marbling score (P = 0.03) and intramuscular fat content (P = 0.07).  These results indicate prepartum maternal dietary energy source may alter fetal adipose tissue development and insulin sensitivity resulting in long-term impacts on progeny¡¯s intramuscular fat deposition. These results also indicate that a greater number of days on a corn-based finishing diet increases insulin resistance in beef cattle.