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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #153693
Title: EFFECTS OF VARYING ENERGY INTAKE AND SIRE BREED ON DURATION OF POSTPARTUM ANESTRUS, INSULIN-LIKE GROWTH FACTOR, AND GROWTH HORMONE IN MATURE CROSSBRED COWS

Author
item Roberts, Andrew
item Jenkins, Thomas

Submitted to: Research Update for Fort Keogh Livestock and Range Research Laboratory
Publication Type: Popular Publication
Publication Acceptance Date: 10/1/2002
Publication Date: 1/15/2003
Citation: ROBERTS, A.J., JENKINS, T.G. EFFECTS OF VARYING ENERGY INTAKE AND SIRE BREED ON DURATION OF POSTPARTUM ANESTRUS, INSULIN-LIKE GROWTH FACTOR, AND GROWTH HORMONE IN MATURE CROSSBRED COWS. RESEARCH UPDATE FOR FORT KEOGH LIVESTOCK AND RANGE RESEARCH LABORATORY. p. 48. 2003.

Interpretive Summary: Previous research has demonstrated that different breeds or biological types of cattle respond differently to limited nutrient environments. In this study, we evaluated how sire breed (Angus, Hereford, Shorthorn, Galloway, Longhorn, Nellore or Salers) influenced length of postpartum anestrus in F1 cows out of Angus or Hereford dams, when cows were fed at one of 3 levels of daily metabolizable energy intake (132 or 189 kcal ME/kg metabolic BW or ad libitum). Concentrations of two metabolic hormones, IGF-1 and GH, were also measured in the blood as indicators of nutritional status (i.e., high GH and low IGF-1 indicate negative energy balance). Length of anestrus was affected by level of energy fed in Galloway, Longhorn, and Nellore sired cows, but not other breeds. Level of energy fed affected concentrations of IGF-1 and GH, and the patterns of changes in these hormones during the postpartum period. As we have observed previously, restricted availability of energy intake resulted in decreasing concentrations of IGF-1 and increasing concentrations of GH over time after calving. These changes indicate that animals in the restricted feeding groups were in a negative energy balance, which corresponds to increased levels of milk productions that occur during the first 2 to 3 months postpartum. However, magnitude of change in IGF-1 observed between the different feeding levels varied by sire breed. Cows sired by Nellore and Longhorn bulls had higher levels of IGF-1 than cows from other sire breeds, yet these cows actually exhibited longer periods of anestrus than cows from other breeds. These results indicate that caution needs to be taken when using levels of IGF-1 as an indicator of nutritional status across different breed types. The present study demonstrates that choice of sire breed to produce crossbred cows influences reproductive performance of cows as measured by length of postpartum anestrus, and through energy balance (as predicted by IGF-1) as levels of energy availability vary.

Technical Abstract: Previous research has demonstrated that different breeds or biological types of cattle respond differently to limited nutrient environments. In this study, we evaluated how sire breed (Angus, Hereford, Shorthorn, Galloway, Longhorn, Nellore or Salers) influenced length of postpartum anestrus in F1 cows out of Angus or Hereford dams, when cows were fed at one of 3 levels of daily metabolizable energy intake (132 or 189 kcal ME/kg metabolic BW or ad libitum). Concentrations of two metabolic hormones, IGF-1 and GH, were also measured in the blood as indicators of nutritional status (i.e., high GH and low IGF-1 indicate negative energy balance). Length of anestrus was affected by level of energy fed in Galloway, Longhorn, and Nellore sired cows, but not other breeds. Level of energy fed affected concentrations of IGF-1 and GH, and the patterns of changes in these hormones during the postpartum period. As we have observed previously, restricted availability of energy intake resulted in decreasing concentrations of IGF-1 and increasing concentrations of GH over time after calving. These changes indicate that animals in the restricted feeding groups were in a negative energy balance, which corresponds to increased levels of milk productions that occur during the first 2 to 3 months postpartum. However, magnitude of change in IGF-1 observed between the different feeding levels varied by sire breed. Cows sired by Nellore and Longhorn bulls had higher levels of IGF-1 than cows from other sire breeds, yet these cows actually exhibited longer periods of anestrus than cows from other breeds. These results indicate that caution needs to be taken when using levels of IGF-1 as an indicator of nutritional status across different breed types. The present study demonstrates that choice of sire breed to produce crossbred cows influences reproductive performance of cows as measured by length of postpartum anestrus, and through energy balance (as predicted by IGF-1) as levels of energy availability vary.