Muscle glycogen and blood parameters in genetic strains of Angus
cattle
C.A. Morris, M.G. Lambert, T.W. Knight and A.D. Fisher
AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton
Proceedings of the New Zealand Society of Animal Production.
2000 60: 132-134
Angus selection and control herds in two long-term breeding
studies were compared for muscle glycogen and blood parameters
pre-slaughter. Trial 1 involved 3 years of bulls (n=85) from a
yearling-weight (W) selection herd and a control (C1) herd, differing by
19% in yearling weight. Trial 2 involved one year of steers (n=45) from
an experiment to increase age at puberty (A+ herd) or to reduce age at
puberty (A- herd), relative to a control (C2) herd, with age at puberty
differing from the C2 mean by 11% (A+) and -10% (A-). In Trial 1, muscle
biopsies were taken for glycogen assay (Years 1 and 2), and blood
samples were taken (Years 1-3) for creatine kinase, cortisol, lactate,
non-esterified fatty acids (NEFA) and glucose; animals in Trial 2 (Year
2 only) were sampled at the same time as Trial 1. Samples were taken at
17 months of age (Year 1), 10 and 19 months (Year 2), and 19 and 20
months (Year 3, with an extra blood trait added). Muscle glycogen
concentration was 19% higher in the W than C1 herd (P<0.05), and it was
significantly lower in the A+ herd than in the other two herds
(P<0.001). Cortisol (P<0.05) and glucose concentrations (P<0.01) were
lower in the W than the C1 herd; NEFA was higher in the C2 herd than in
the A- or A+ herds (P<0.05). No other blood parameters differed between
herds. Repeatabilities for the 5 main blood traits in Trial 1 ranged
from 0.14 to 0.38, being highest for creatine kinase (if excluding
outliers), but repeatabilities were all low in Trial 2 (highest value
only 0.13). The main conclusions came from Trial 1, in which most data
had been collected, namely that across-year differences were found for 3
traits between herds (muscle glycogen, cortisol and glucose).
Keywords: NZSAPAB;
muscle glycogen; metabolites; enzymes; cattle; genetics.
Last Updated 12-07-2000
