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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #178510
Title: ASSOCIATIONS OF GROWTH AND CARCASS TRAITS WITH ATTAINMENT OF PUBERTY IN HEIFERS FED AT TWO LEVELS

Author
item Roberts, Andrew
item PAISLEY, S - U OF WY LARAMIE
item Geary, Thomas
item Grings, Elaine
item Macneil, Michael

Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2005
Publication Date: 6/15/2005
Citation: Roberts, A.J., Paisley, S.I., Geary, T.W., Grings, E.E., Macneil, M.D. 2005. Associations of growth and carcass traits with attainment of puberty in heifers fed at two levels. Western Section of Animal Science Proceedings 56:333-335.

Interpretive Summary: Associations of growth and ultrasound carcass measurements with attainment of puberty by 13.5 mo of age were evaluated in heifers developed under two levels of feeding during a 160-d postweaning study. Heifers from the CGC composite (½ Red Angus, ¼ Charolais, ¼ Tarentaise) were randomly assigned to either control (fed to appetite; n=63) or restricted (fed at 80% of that consumed by controls adjusted to a common BW basis; n=62) feeding. Heifers were individually fed a diet of 67% corn silage, 18% alfalfa and protein-mineral supplement (DM basis) in pens equipped with Calan gates. Ultrasound measurements of LM area, intramuscular fat (IMF), and subcutaneous fat depth (FT) were made at d 140 (about 1 yr of age). Restricted feeding decreased (P < 0.01) DMI (4.2 vs. 5.7 kg/d), BW (297 vs. 322 kg on d 140), ADG (0.61 vs. 0.78 kg/d), LM area (53 vs. 59 cm2), IMF (3.4 vs. 3.7 %) and FT (4.1 vs. 4.7 mm) when compared to control. Concentrations of progesterone in blood samples collected at 9 to 11 d intervals were used to ascertain pubertal status, which did not differ between restricted (29%) and control heifers (41%) by 13.5 mo of age (d 180). Logistical regression was used to analyze effects of treatment and individual traits on pubertal status at d 180. Proportion of heifers that were pubertal increased (P < 0.05) with increases in fat (IMF or FT) or ADG, irrespective of treatment. Increases in hip height, BW and LM area at 140 d were each associated (P < 0.05) with increases in puberty in control, but not restricted heifers. Pubertal status did not vary in association with gain to feed ratio or residual feed intake. Increased propensity for fat deposition and ADG positively influenced attainment of puberty whereas variations in efficiency of gain or residual feed intake did not.

Technical Abstract: Associations of growth and ultrasound carcass measurements with attainment of puberty by 13.5 mo of age were evaluated in heifers developed under two levels of feeding during a 160-d postweaning study. Heifers from the CGC composite (½ Red Angus, ¼ Charolais, ¼ Tarentaise) were randomly assigned to either control (fed to appetite; n=63) or restricted (fed at 80% of that consumed by controls adjusted to a common BW basis; n=62) feeding. Heifers were individually fed a diet of 67% corn silage, 18% alfalfa and protein-mineral supplement (DM basis) in pens equipped with Calan gates. Ultrasound measurements of LM area, intramuscular fat (IMF), and subcutaneous fat depth (FT) were made at d 140 (about 1 yr of age). Restricted feeding decreased (P < 0.01) DMI (4.2 vs. 5.7 kg/d), BW (297 vs. 322 kg on d 140), ADG (0.61 vs. 0.78 kg/d), LM area (53 vs. 59 cm2), IMF (3.4 vs. 3.7 %) and FT (4.1 vs. 4.7 mm) when compared to control. Concentrations of progesterone in blood samples collected at 9 to 11 d intervals were used to ascertain pubertal status, which did not differ between restricted (29%) and control heifers (41%) by 13.5 mo of age (d 180). Logistical regression was used to analyze effects of treatment and individual traits on pubertal status at d 180. Proportion of heifers that were pubertal increased (P < 0.05) with increases in fat (IMF or FT) or ADG, irrespective of treatment. Increases in hip height, BW and LM area at 140 d were each associated (P < 0.05) with increases in puberty in control, but not restricted heifers. Pubertal status did not vary in association with gain to feed ratio or residual feed intake. Increased propensity for fat deposition and ADG positively influenced attainment of puberty whereas variations in efficiency of gain or residual feed intake did not.