Reproductive and Physiological Responses of Holstein Heifers to Controlled and Natural Climatic Conditions

Gangwar, P. C.; Branton, C.; Evans, D.L.

doi:10.3168/jds.s0022-0302(65)88200-5

Cited by 76 publications

(20 citation statements)

References 8 publications

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“…Estrus was readily recognizable in Fulani heifers, contrary to an early belief that estrus is difficult to detect in zebu cattle (2). Estrous expression in Bos taurus cattle has not been adversely altered by adaptation to the hot environment, thus contradicting previous reports of estrus being of short duration (8,11) or hardly detectable (19) in hot weather. However, the economic importance of the subestrus that was noticed on a few occasions in both species is the fact that a heifer showing subestrus may not be detected and thus miss being bred, if a less rigorous method of heat check is employed on a farm.…”

Section: Discussioncontrasting

confidence: 75%

Estrous Cycles in Bos Indicus and Bos Taurus Heifers Acclimatized to the Hot Humid seasonal equatorial Climate

Adeyemo¹,

Heath²,

Steinbach³

et al. 2010

Zentralblatt Für Veterinärmedizin Reihe A

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Summary The estrous cycle was characterised in German Brown, Holstein and White Fulani heifers in a hot humid seasonal equatorial climate (Nigeria) during a 15‐month period. The mean values, with standard error, given below are in the order of the breeds. Average estrous cycle length was 21 ± 0.3, 20.1 ± 0.7 and 21.4 ± 0.2 days, and duration of estrus 16.2 ± 0.7, 15 ± 0.8 and 14.6 ± 0.8 hours, respectively. Estrous cycle length was significantly (P < 0.05) shorter in the Holsteins than the other breeds. The breed difference in the duration of estrus between the Brown and Fulani heifers was significant (P < 0.05). Estrus recurred throughout the year and commenced mostly in the morning hours. Staying‐for‐mounting and vaginal fluid flow were definitive estrual signs. Subestrus and mid‐cycle estrus occurred very infrequently. The ovulation intervals after the end of estrus (14.2 ± 0.6, 14.7 ± 0.6 and 15.1 ± 0.9, respectively) showed no significant (P > 0.05) breed differences. The effect of the season on the different parameters was not significant (P > 0.05). The results suggest that the environment of the present study does not adversely affect the sexual cycles of temperate‐evolved and zebu cattle. Zusammenfassung Der Brunstzyklus bei an das feucht‐heiße Aequatorialklima angepaßten Rindern der Bos indicus‐ und Bos taurus‐Rasse Während 15 Monaten wurde bei Rindern verschiedener Rassen (German Brown, Holstein White Fulani) in einem feucht‐heißen Äquatorklima (Nigeria) der Brunstzyklus untersucht. Die Länge des Brunstzyklus betrug (Rassenreihenfolge wie oben): 21 ± 0,3, 20,1 ± 0,7 und 21,4 ± 0,2 Tage. Die Brunstdauer betrug: 16,2 ± 0,7, 15,0 ± 0,8 und 14,6 ± 0,8 Stunden. Der Brunstzyklus der Holstein‐Rinder war signifikant kürzer als derjenige der beiden andern Rassen. Die Differenz der Brunstdauer zwischen der Brown‐ und Fulani‐Rasse war signifikant (P < 0,05). Die Brunst trat während des ganzen Jahres auf, und zwar meistens am Vormittag. Typische Brunstsymptome waren: Duldung des Deckaktes sowie Vaginalausfluß. Fälle von stiller Brunst und Brunst in der Zyklusmitte traten selten auf. Das Intervall zwischen dem Brunstende und der Ovulation zeigte keine signifikanten Rassenunterschiede. Es betrug 14,2 ± 0,6, 14,7 ± 0,6 und 15,1 ± 0,9 Stunden (P > 0,05). Die verschiedenen Parameter zeigten keine signifikanten Saisoneffekte. Die Ergebnisse sprechen dafür, daß das Milieu den Sexualzyklus von Rindern aus den gemäßigten Klimaten und der Zeburasse nicht wesentlich beeinträchtigt. Résumé Le cycle des chaleurs chez des bovins adaptés au climat équatorial humide des races Bos indicus et Bos taurus Le cycle des chaleurs de bovins de races différentes (German Brown, Holstein et White Fulani) a été observé durant 15 mois dans un climat équatorial humide (Nigeria). La durée du cycle a été dans l'ordre des races cités: 21 ± 0,3; 20,1 ± 0,7 et 21,4 ± 0,2 jours. La durée des chaleurs fut de 16,2 ± 0,7; 15,0 ± 0,8 et 14,6 ± 0,8 heures. Le cycle des chaleurs des bovins Holstein fut significativement plus court que celui des deux autre...

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Section: Discussioncontrasting

confidence: 75%

Estrous Cycles in Bos Indicus and Bos Taurus Heifers Acclimatized to the Hot Humid seasonal equatorial Climate

Adeyemo¹,

Heath²,

Steinbach³

et al. 2010

Zentralblatt Für Veterinärmedizin Reihe A

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“…Heat stress reduces the length (Monty and Wolff, 1974;Abilay et al, 1975) and intensity (Gangwar et al, 1965) of estrus. In Virginia, Nebel et al (1997) reported that Holsteins in estrus during summer had 4.5 mounts per estrus vs 8.6 for those in winter.…”

Section: Changes In Estrus Caused By Heat Stressmentioning

confidence: 99%

Strategies for managing reproduction in the heat-stressed dairy cow

Hansen

Aréchiga

1997

Journal of Animal Science

168

136

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Establishment and maintenance of pregnancy is difficult in lactating dairy cows exposed to heat stress because of reductions in estrous detection rate and the proportion of inseminated cows that maintain pregnancy. The most common approach to ameliorate heat stress in developed countries has been to alter the cow's environment through provision of shade, fans, sprinklers, and so on. Nonetheless, seasonal variation in reproductive function persists. Increased understanding of bovine reproductive function and its alteration by heat stress has led to additional strategies for reducing deleterious consequences of heat stress on reproduction. These include hormonally induced timed artificial insemination, which can reduce losses in reproductive efficiency caused by poor detection of estrus, and embryo transfer, which can increase pregnancy rate by allowing embryos to bypass the period when they are most sensitive to elevated temperature (i.e., in the first 1 to 2 d after breeding). Other efforts are directed toward developing methods to protect the embryo from harmful actions of elevated temperature. Approaches being studied include manipulation of embryonic synthesis of heat shock proteins and use of antioxidants to reduce free radical damage associated with heat stress. It may also be possible to reduce the magnitude of hyperthermia caused by heat stress. This might be possible physiologically, for example by feeding of agents that affect thermoregulatory systems, or genetically by selecting for specific traits conferring thermal resistance. Finally, the development of bovine somatotropin as a lactational promotant means that it may be possible to extend lactations beyond 305 d and voluntarily discontinue inseminations during periods of heat stress.

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“…Experimental heat stress reduced the length of estrus (Gangwar et al, 1965 ;Abilay et al, 1975 ), and estrous cows during the summer had reduced walking (L ó pez - Gatius et al, 2005 ) and mounting activities (Nebel et al, 1997 ). Experimental heat stress reduced the length of estrus (Gangwar et al, 1965 ;Abilay et al, 1975 ), and estrous cows during the summer had reduced walking (L ó pez - Gatius et al, 2005 ) and mounting activities (Nebel et al, 1997 ).…”

Section: Detection Of Estrusmentioning

confidence: 99%

Managing Reproduction During Heat Stress in Dairy Cows

Hansen

2011

Dairy Production Medicine

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Heat stress can compromise reproductive function of lactating dairy cows throughout much of the world. Among the key events associated with reduced reproductive function are reduced expression of estrus, disruptions in follicular and oocyte function, increased embryonic mortality, and reductions in fetal development. Reproductive function during heat stress can be improved by modifying animal housing to reduce the magnitude of heat stress. In addition, manipulation of physiological function can mitigate some deleterious effects of heat stress. Effects on estrus detection can be reduced by incorporation of estrus detection aids and eliminated by utilization of timed artifi cial insemination protocols. Effects on fertility can be reduced by use of embryo transfer. Other approaches, such as feeding antioxidants, offer some promise for improving fertility, whereas others, such as hormonal treatments, have not resulted in consistent improvements in fertility during heat stress. In the future, it may be possible to select cows for resistance to heat stress as genetic markers for thermotolerance at the physiological and cellular level are identifi ed.Heat stress adversely affects fertility of dairy cattle in most temperate regions of the world where dairy cattle are raised. The magnitude and duration of the reduction in fertility during seasonal heat stress is greater in Dairy Production Medicine, First Edition. Edited by Carlos A. Risco, Pedro Melendez Retamal.

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Reproductive and Physiological Responses of Holstein Heifers to Controlled and Natural Climatic Conditions

Cited by 76 publications

References 8 publications

Estrous Cycles in Bos Indicus and Bos Taurus Heifers Acclimatized to the Hot Humid seasonal equatorial Climate

Estrous Cycles in Bos Indicus and Bos Taurus Heifers Acclimatized to the Hot Humid seasonal equatorial Climate

Strategies for managing reproduction in the heat-stressed dairy cow

Managing Reproduction During Heat Stress in Dairy Cows

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