EurekaMag.com logo
+ Site Statistics
References:
48,252,460
Abstracts:
22,798,453
+ Resolve Accession
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
Submit PDF Full TextSubmit PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Investigating optimal bull:heifer ratios required for estrus-synchronized heifers


, : Investigating optimal bull:heifer ratios required for estrus-synchronized heifers. Journal of Animal Science 71(2): 291-297

The objectives of this study were to determine 1) the effect of bull:heifer ratio on reproductive performance and associated costs and returns on heifers in synchronized estrus and 2) the effect of estrus synchronization on reproductive performance and economic variables, in a multiple-sire, pasture breeding situation. Eight hundred yearling beef heifers and 28 mature, sexually experienced beef bulls were allotted to four treatments (two replicates per treatment) at bull:heifer ratios of 2 per 100 (1:50; Treatment 1), 2 per 100 (1:50; Treatment 2), 4 per 100 (1:25; Treatment 3), and 6 per 100 (1:16; Treatment 4). Treatment 1 (control) used nonsynchronized heifers, whereas heifers in Treatments 2, 3, and 4 were synchronized using the 33-d melengestrol acetate (MGA)-prostaglandin F2 alpha (PGF2 alpha) program. Pregnancy results after a 28-d breeding season indicate that there may be a limit to how many estrus-synchronized heifers bulls can impregnate. Treatment 2 showed a 6% decrease (P < .10) in pregnancy rate (77%) compared with Treatment 3 (83%), indicating that the bulls probably were not able to service all the synchronized heifers. Treatments 3 and 4 had similar pregnancy rates (83 and 84%, respectively). Treatment 4 had a 3-d advantage (P < . 01) over Treatment 3 in average day of conception. However, based on economic analysis, Treatment 3 exhibited greater returns. Estrus synchronization failed to provide any advantage in pregnancy rate or day of conception. For unknown reasons, the control, nonsynchronized heifers cycled and conceived as if they were synchronized. Treatment 2 had a 5% decrease in pregnancy rate compared with Treatment 1 (77 vs 82%; P < .10) with no difference in average day of conception. Consequently, Treatment 1 (nonsynchronized) exhibited greater economic returns. Results of this study indicated that the optimal bull:heifer ratio for estrus-synchronized heifers was 1:25. In this study, estrus synchronization failed to provide an advantage in terms of reproductive performance or economic efficiency.

(PDF 0-2 workdays service)

Order PDF Full Text

Close
Close

Click here to order any other PDF Full Text


Accession: 002416683

PMID: 8440646

PDF Full Text: Submit


Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:
Close
Close

Other references

Skuhravy, V., 1975: Die Kiefernnadelgallmucke Thecodiplosis brachyntera (Schwagr.) ein Modelobjekt fur i kologische Untersuchungen (Diptera, Cecidomyiidae). Folia Prirod Fak Univ Purkyne, 151: 41-44

Chichester, F. W., 1983: Premining evaluation of forage grass growth on mine soil materials from an east-central Texas lignite site: 2. Soil profile horizons. Several warm-season forage grasses and a cool-season pasture mix of oats plus clover were grown in a greenhouse on mixtures of soil profile horizon materials from an unmined lignite site in east-central Texas and the suitability of various soil ma...

Hatt, P., 1927: Porospora legeri de Beauchamp (= Porospora gallopro-vincialis Leger et Duboscq) et les premiers stades de son evolution chez I'Eriphia. Archives de Zoologie Experimentale et Generale (Notes et Rev ) Paris, 67: 8-11

Cory J.G.; Fleischer A.E., 1980: Mode of inhibition of tumor cell ribo nucleotide reductase by 2 3 di hydro 1h pyrazolo 2 3 a imidazole nsc 51143. 2,3-Dihydro-1H-pyrazolo[2,3-a]imidazole (NSC 51143; IMPY) inhibits partially purified ribonucleotide reductase from Ehrlich [mouse] tumor cells. CDP and ADP reductase activities were inhibited by IMPY, although ADP reductase activity was inhibited...

Segelman F.H.; Kelton E.; Terzi R.M.; Sofia R.D., 1986: Net effect of delta 9 tetrahydrocannabinol on rat liver monoxygenases. During routine screening of xenobiotics for effects on rat liver cytochrome P450 levels, oral administration of 20 and 100 mg/kg .DELTA.9-tetrahydrocannabinol (THC) as single or multiple doses produced statistically significant decreases in cytoch...

Barbieri, Geraldo.; Marins, Marcos de Afonso., 1995: A study of reproduction dynamics of the females of Astyanax bimaculatus Linnaeus, 1758 in the Lobo Reservoir Sao Paulo state Osteichthyes, Characidae Estudo da dinamica da reproducao de femeas de Astyanax bimaculatus Linnaeus, 1758 da represa do Lobo, estado de Sao Paulo Osteichthyes, Chacidae. Females of Astyanax bimaculatus were caught at the Lobo reservoir (Sao Paulo) from, February 1991 to January 1992, and the condition factor, the hepatosomatic index fluctuations were related with the gonadal development. Condition factor fluctuati...

Hosein, Hazem; Anderson, Aileen J.; Huang, Wenchen; Young, Wise; Cotman, Carl W., 1998: Complement pathway activation following contusion-induced spinal cord injury. Society for Neuroscience Abstracts 24(1-2): 1151

Xue RuiDe; Zeng YiFang; Xu RongMan; Zhang JinTong; Lu BaoLin, 1992: Studies on the effectiveness of alpha-cypermethrin-impregnated mosquito net against Culex pipiens pallens in the experimental case. Mosquito nets impregnated with alpha-cypermethrin (20 mg/msuperscript 2) were tested against C. pipiens pallens (Beijing strain) in the experiments using exit-window traps to catch the nocturnal females. In addition, net fibres impregnated with al...

Bonham, G.S.; Brock, D.B., 1985: The relationship of diabetes with race, sex, and obesity. Noninsulin-dependent diabetes typically has its onset in the adult years, and appears to have both genetic and non-genetic factors in its etiology. Data from the 1976 National Health Interview Survey were used to study the independent and interact...

Coscia N.; Saginati M.; Risso A.M.; Zardi L., 1990: Relative amount of ed b containing fn messenger rna in cultured normal human fibroblasts of different tissue origin. Journal of Cell Biology 111(5 PART 2): 394A