24146
document
Incidence of puberty in beef heifers fed high- or low-starch diets for different periods before breeding . Spring-born Hereford x Angus heifers ( n = 206 ) were used to determine effects of energy supplementation programs and amount of starch in the diet on incidence of puberty . In Exp . 1 , heifers ( 205 +/- 5 kg ; n = 68 ) grazing dormant native pasture were fed 0.9 kg/d ( as-fed basis ) of a 42 % CP supplement from November until February 14 . Heifers were stratified by weaning weight and allotted randomly to treatment before breeding ( May to July ) . Treatments were 1 ) 0.9 kg ( as-fed basis ) of a 42 % CP supplement/d and pasture ( control ) ; 2 ) a high-starch ( HS ) diet ( 73 % corn ; 53 % starch ) fed in a drylot for 60 d ( HS-60 ) ; 3 ) a HS diet fed in drylot for 30 d ( HS-30 ) ; or 4 ) a low-starch ( LS ) diet ( 49 % corn ; 37 % starch ) self-fed on pasture for 30 d ( LS-30 ) . The HS-60 and HS-30 heifers were limited-fed to gain 0.9 kg/d , and the LS-30 heifers had ad libitum access to the diet . High-starch-60 and LS-30 heifers were heavier ( P < 0.05 ) than control and HS-30 heifers at the beginning of the breeding season . Thirty-one , 25 , and 26 % more HS-60 heifers were pubertal ( P < 0.05 ) on May 1 compared with LS-30 , HS-30 , and control heifers , respectively . At puberty , HS-60 heifers were 24 and 22 d younger ( P < 0.05 ) than LS-30 and control heifers , and 31 kg lighter ( P < 0.01 ) than LS-30 heifers . In Exp . 2 , heifers grazed dormant pasture and were fed 0.9 kg ( as-fed basis ) of a 42 % CP supplement/d from weaning in October to late February ; then heifers were assigned randomly to treatments for 60 d before the breeding season . In two years , control heifers ( n = 46 ) grazed pasture and received 0.9 kg of SBM supplement/d ; LS ( n = 46 ) heifers were self-fed a distiller 's grain and soybean hull-based diet in drylot ; and HS heifers ( n = 46 ) were limited-fed a corn-based diet in drylot . During treatment , HS and LS heifers had greater weight gains than control heifers . Pubertal BW ( 313 +/- 6 kg ) was not influenced by treatment , but HS and LS heifers were younger ( P < 0.03 ) than control heifers at puberty . During a 60-d breeding period , the incidence of puberty was greater ( P < 0.05 ) for HS and LS heifers than for control heifers and was greater ( P < 0.05 ) in HS than in LS heifers in Year 1 . Feeding a LS or a HS diet for 30 d before breeding may be inadequate to stimulate puberty in beef heifers , but feeding a diet with a greater amount of starch for 60 d before breeding may increase the incidence of puberty during breeding of heifers that have inadequate yearling weight .
24147
Intervention_Pharmacological
high- or low-starch diets
24148
Intervention_Pharmacological
energy supplementation programs and amount of starch
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Intervention_Physical
CP supplement
24150
Intervention_Pharmacological
CP supplement/d and pasture
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Intervention_Pharmacological
a high-starch ( HS ) diet ( 73 %
24152
Intervention_Physical
HS diet fed in drylot
24153
Intervention_Physical
a low-starch ( LS ) diet
24154
Intervention_Educational
self-fed on pasture
24155
Intervention_Pharmacological
HS-60
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Intervention_Pharmacological
HS-30
24157
Intervention_Pharmacological
LS-30
24158
Intervention_Pharmacological
42 % CP supplement/d
24159
Intervention_Pharmacological
SBM supplement/d
24160
Intervention_Pharmacological
distiller 's grain and soybean hull-based diet
24161
Intervention_Pharmacological
limited-fed a corn-based diet
24162
Intervention_Pharmacological
HS
24163
Intervention_Pharmacological
LS
24164
Intervention_Pharmacological
LS
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Intervention_Pharmacological
HS diet
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Outcome_Physical
Incidence of puberty
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Outcome_Physical
weight
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Outcome_Physical
heavier
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Outcome_Physical
weight gains
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Outcome_Physical
Pubertal BW
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Outcome_Physical
incidence of puberty
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Outcome_Physical
puberty
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Outcome_Physical
incidence of puberty