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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #89962
Title: JOINT EFFECTS OF FETAL AND MATERNAL GENOTYPES ON CALVING DIFFICULTY

Author
item Bellows, Robert
item STAIGMILLER, R - RETIRED USDA-ARS
item Short, Robert

Submitted to: Governors Conference on the State of the Livestock Industry
Publication Type: Other
Publication Acceptance Date: 8/1/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rapid growth large frome (RL, n=61) or average growth medium from (AM, n=71) biotype heifers fed to achieve either moderate (MOD, .6kg/d) or high ADG (HI, 1.0 kg/d) were used to determine whether puberty occurs at similar body composition or metabolic status. Live animal estimates of body composition & blood samples for assessment of metabolic status were taken at 13f.2d after estrus for all heifrs. Body composition and meta- bolic status were assessed every 56 d from 7 mo of age until puberty in a subset of 80 heifers representing all biotype-diet combinations. At puberty 32 of these 80 heifers were slaughtered & physical and chemical composition of the empty body were determined. High-gain diet heifers were younger, heavier, taller and more muscular at puberty than MOD heifers. Slaughter measurements paralleled live animal estimates; bodies of HI and RL heifers contained more carcass and noncarcass components than those of MOD & AM heifers, respectively. Carcasses of RL & HI heifers were more muscular & fatter than AM & MOD heifers. At puberty, HI heifers had a greater mass of moisture, fat, and fat-free organic matter (FFOM) than MOD, whereas RL heifers had more moisture, ash, & FFOM than AM. Percentage of fat was greater in HI than in MOD heifers. Diet did not influence concentration of IGF-I or glucose, and metabolic markers were unaffected by biotype. No dramatic changes in body composition or metabolic signals were detected before puberty. Puberty did not occur at similar body composition or metabolic status in all heifers.

Technical Abstract: Rapid growth large frame (RL, n=61) or average growth medium frame (AM, n=71) biotype heifers fed to achieve either moderate (MOD, .6 kg/d) or high ADG (HI, 1.0 kg/d) were used to determine whether puberty occurs at similar body composition or metabolic status. Live animal estimates of body composition & blood samples for assessment of metabolic status were taken at 13f.2 d after estrus for all heifers. Body composition and meta bolic status were assessed every 56 d from 7 mo of age until puberty in a subset of 80 heifers representing all biotype-diet combinations. At pu berty, 32 of these 80 heifers were slaughtered & physical and chemical composition of the empty body were determined. High-gain diet heifers were younger, heavier, taller, & more muscular at puberty than MOD heif- ers. Slaughter measurements paralleled live animal estimates; bodies of HI and RL heifers contained more carcass and noncarcass components than those of MOD & AM heifers, respectively. Carcasses of RL & HI heifers were more muscular & fatter than AM & MOD heifers. At puberty, HI heifers had a greater mass of moisture, fat, & fat-free organic matter (FFOM) than MOD, whereas RL heifers had more moisture, ash, & FFOM than AM. Per centage of fat was greater and percentage of moisture was less in bodies of HI than in those of MOD heifers. Concentrations of blood urea nitrogen and insulin were greater in HI than in MOD heifers. Diet did not influ ence concentration of IGF-I or glucose, and metabolic markers were unaf fected by biotype. No dramatic changes in body composition or metabolic signals were detected before puberty. Puberty did not occur at similar body composition or metabolic status in all heifers.