Influence of pregnancy on body weight, ruminal characteristics, and visceral organ mass in beef heifers

J Anim Sci. 2001 Sep;79(9):2481-90. doi: 10.2527/2001.7992481x.

Abstract

Crossbred heifers (initially 24 mo, approximate age and 378 +/- 32.1 kg BW) were used to evaluate the influence of pregnancy and advancing gestation on DMI, BW, carcass weight, ruminal characteristics, and visceral organ mass. Heifers (naturally serviced (n = 22; nonpregnant controls, n = 17), were grouped in common pens. Heifers were provided corn silage and hay-based diets formulated to provide 0.45 kg of ADG. Treatments were pregnancy and nonpregnancy; pregnant and nonpregnant heifers were slaughtered on d 40, 120, 200, and 270. Live weight at slaughter and BW change throughout the trial were not influenced by pregnancy (P > 0.1). Carcass weight per unit of BW was decreased due to pregnancy (P < 0.05) and an interaction was found in eviscerated BW (EvBW; P < 0.1), with the pregnant heifers having greater live weights, carcass weights, and EvBW at the d-200 slaughter period. Ruminal fluid fill and total fill (g/kg BW) declined as slaughter period advanced, resulting in the pregnant heifers having less fill at d 270 (P< 0.07). However, ME intake was not different between pregnant and nonpregnant heifers (P > 0.1) at any of the slaughter periods. Heart mass responded differently when nonpregnant and pregnant were analyzed over time and an interaction was detected as slaughter period advanced (P < 0.1). Liver, duodenum, jejunum, and large intestinal mass were not responsive to pregnancy (P > 0.1). Data indicate that ruminal fill is altered by pregnancy but visceral organ mass is not greatly changed by treatment.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Body Weight / physiology*
  • Cattle / anatomy & histology
  • Cattle / physiology*
  • Energy Intake
  • Female
  • Fermentation
  • Organ Size / physiology
  • Pregnancy
  • Pregnancy, Animal / metabolism
  • Pregnancy, Animal / physiology*
  • Rumen / metabolism
  • Rumen / physiology*
  • Time Factors
  • Viscera / anatomy & histology*
  • Viscera / physiology