Arkansas - Agricultural Communication Services - University of ...

Supplementation of Beef Cows and Heifers Consuming
High Quality Fescue Hay
D. L. Kreider, R. W. Rorie, N. Post, and K. Cole 1
Story in Brief
Seventy-six spring calving, cross-bred cows and heifers of mostly Angus breeding were used to determine the
impact of pre- and post-partum supplementation on post-partum reproductive performance when consuming harvested
high-quality cool-season forages. Forage used in the study was tall fescue hay having 16.05% CP and 58.4% TDN.
Cows and heifers received either no supplement (Control), 2 lb of Corn (Corn) or 2 lb of a 17% CP corn-soybean meal
supplement (Corn-Soy). Cows and heifers were placed on supplement before calving and continued on the same supplement
into the post-partum period. Control (non-supplemented) heifers had greater weight loss in the post-partum
period (P < 0.01), lower weaning weights (P < 0.10) and ADG (P < 0.08) by nursing calves than Corn or Corn-Soy supplemented
heifers. Cows receiving the Corn-Soy supplement had a shorter calving interval (P = 0.10) than Control cows.
Reproductive performance was poor in all treatment groups, suggesting that intake of forage in all groups was not adequate
to meet nutritional requirements.
Introduction
Feed costs constitute 60 to 70% of the annual cost of
maintaining a beef cow and a large part of feed cost is represented
by the cost of supplements. Recent data (Davis, 2000)
indicate that 89% of the hay samples assayed in Arkansas
were adequate in protein for a dry gestating cow and 59% of
samples had adequate protein for lactating cows. In the same
study, TDN was adequate for dry gestating cows in 75% of
the hay tested, while only 28% of the samples had adequate
TDN for lactating cows. These data suggest that dry gestating
cows and, in some instances, lactating cows can be maintained
on forage alone or on an energy supplement alone
since protein is adequate in many cases. It is well established
that adequate nutrition of the cow in the pre- and post-partum
period is a critical factor in achieving successful post-partum
reproduction (Richards et al., 1986; Selk et al., 1988). It has
also been demonstrated that excessively high dietary protein
intake has been associated with decreased fertility (Jordan
and Swanson 1979; Kaim et al., 1983; Canfield et al. 1990).
Since protein supplements are relatively high in cost compared
to energy supplements and excess protein can have
detrimental effects on reproductive performance, minimizing
the supplemental protein fed may be beneficial to producers.
The following study was conducted to compare the effects of
no supplement, an energy supplement and a 17% CP supplement
on the post-partum reproductive performance of beef
cows consuming high quality tall fescue hay.
Experimental Procedures
Seventy-six spring calving, cross-bred cows and heifers
with mostly Angus breeding were used to determine the
impact of pre- and post-partum supplementation on post-partum
reproductive performance of cows consuming harvested
high-quality cool-season hay (Table 1). Before calving, animals
were blocked by body weight, parity and body condition
score (BCS) and randomly assigned to one of three treatment
groups. Animals received either no supplement (Control), 2
lb of corn per animal per day (Corn), or 2 lb per animal per
day of a 17% CP corn-soybean meal supplement (Corn-Soy).
Supplementation was started at approximately 7 to 8 weeks
pre-partum and animals remained on the same supplements
until the start of the breeding season. Cows were maintained
as a single group, and were sorted from calves once daily
(Monday-Saturday) and fed supplement individually.
Treatment groups remained together in the same pen or pasture
at all times except at daily supplementation. Supplements
were fed to all groups until the start of the breeding season.
Ad libitum access to the mixed fescue hay, mineral supplement,
and water was available at all times.
In order to evaluate the effects of supplements on body
weight change and energy reserves, body weights and BCS
were taken at the beginning of the trial and at the start of the
60-day breeding season. In order to access reproductive status
via serum progesterone concentration, all animals were
bled weekly beginning at 3 weeks post-partum and continuing
until the start of the breeding season. Blood samples, collected
by jugular venipuncture, were stored on ice and
1 All authors are associated with the Department of Animal Science, Fayetteville.
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