Photoperiodicity in cattle. I. Seasonal changes in coat character and their importance in heat regulation

Yeates, N. T. M.

doi:10.1071/ar9550891

Cited by 69 publications

(23 citation statements)

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“…Coat length and thickness are important traits linked to animal adaptation in the tropics, where longer hair is linked to animals more affected by heat stress (Yeates 1955). Silva (1998) has shown that number of hairs per unit area is important in protection of the skin against ultraviolet radiation.…”

Section: Discussionmentioning

confidence: 99%

Skin and coat traits in sheep in Brazil and their relation with heat tolerance

McManus¹,

Louvandini

Gugel

et al. 2010

Trop Anim Health Prod

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The objective of this study was to evaluate and compare physical parameters in groups of sheep with different phenotypic characteristics in the Centre-west region of Brazil. Five groups of sheep, with nine animals per group, were selected, three groups of Santa Inês animals with different coat colours (white, brown and black), one group with crossbred animals (Santa Inês × Bergamasca) and one group with animals of the Bergamasca breed. The following traits were evaluated: coat thickness, number and length of hair, pigmentation level in the coat and the skin as well as the percentage area of sweats glands in the skin tissue, carried out by histological analysis. The number of hairs and the area of sweats glands were not significantly different between the evaluated groups. The Bergamasca breed showed low pigmentation of the skin and long hairs. The levels of pigmentation of the hair and of the skin were highly correlated. Between the Santa Inês groups, the group with white hair showed the better parameters for heat adaptation, while the brown hair group showed the lower heat adaptation when compared with another hair breed groups.

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Section: Discussionmentioning

confidence: 99%

Skin and coat traits in sheep in Brazil and their relation with heat tolerance

McManus¹,

Louvandini

Gugel

et al. 2010

Trop Anim Health Prod

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“…Finch et al (1984) found that deep, woolly coats were associated with resistance to heat loss, high body temperatures, and poor performance. Clipping the coat reduced skin and rectal temperatures, as well as respiration rate, and relieved distress under extreme heat conditions (Yeates 1954(Yeates , 1955. Sleek coats have been associated with higher rates of sweating (Schleger and Bean 1971) and growth (Turner and Schleger 1960) than woolly coats.…”

Section: Cattle Coat Characteristicsmentioning

confidence: 99%

Heat stress in cattle and the effect of shade on production and behaviour: a review

Blackshaw¹,

Blackshaw²

1994

Aust. J. Exp. Agric.

343

289

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At high temperatures, evaporative cooling is the principal mechanism for heat dissipation in cattle. It is influenced by humidity and wind speed and by physiological factors such as respiration rate, and density and activity of sweat glands. Following exposure to heat, cattle appear to acclimatise within 2-7 weeks. The failure of homeostasis at high temperatures may lead to reduced productivity or even death. Knowledge of characteristic behavioural signs of increasing heat stress may alert cattle handlers to impending heat distress, particularly in areas of potential climatic extremes of high temperatures and humidities. Reduction of the heat increment of feeding by dietary manipulation may partially protect cattle from forecast heat stress. Under high heat stress, Bos indicus breeds and their crosses have better heat regulatory capacities than Bos taurus breeds, due to differences in metabolic rate, food and water consumption, sweating rate, and coat characteristics and colour. Also, because Bos taurus have a higher heat loading at the skin, they must evaporate substantially more sweat than Bos indicus to maintain normal body temperatures. Welfare concerns exist about heat stress and the provision of shade for feedlot cattle. In hot weather, cattle actively seek shade, which may reduce the radiant heat load by 30% or more. Under conditions of extreme heat load, shading may maintain production and reduce deaths from heat stroke. Shading of feed and water also offers production advantages for British and European breeds of cattle.

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“…Heart rate was not useful as a physiological parameter in predicting heat tolerance, as it can be influenced by various environmental factors, unrelated to temperature, such as stress management caused at the time of measurement. The Santa Ines breed was separated from other breeds of animals for morphological characteristics as well for physiological characteristics and body temperatures (Figure 3) as it presented a highly pigmented epidermis, which makes the penetration of ultraviolet rays difficult as well as showing shorter hair of larger diameter and shallower hair layer thickness at the withers, T12 and rump which favors the elimination of latent heat via skin evaporation (Table 4), corroborating with YEATES (1955), who confirmed the hair length as an important characteristic related to animal adaptation in the tropics, as longer the hair the worse is the animal adaptation to heat stress. Müller (1989) also stated that the length and diameter of the hair influence the heat adaptation, since, short, smooth and thin hair provides better heat dissipation, and among the breeds with long, thick coats, the Dorper and Texel breeds had the highest values of brightness (Table 4) which favors greater absorption for solar short-wave radiation, and therefore holds greater amount of thermal energy.…”

Section: Resultsmentioning

confidence: 52%

Breed comparison for heat adaptation in rams using multivariate analysis

Júnior¹,

Lucci²,

Peripolli³

et al. 2016

Biosci. J.

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ABSTRACT:In this study, a multivariate analysis of morphological and physiological characteristics was performed on clinically healthy rams from six breeds (Santa Ines, Bergamasca, Dorper, Texel, Ile de France and Hampshire Down) to determine if these characteristics were able to separate and determine the most important variables in the differentiation of breeds for heat adaptation. To characterize the thermal environment, mean temperature was 23°C and relative humidity ranged between 30.6-55.6%. Morphological and physiological data were subjected to multivariate statistical tests including principal components (PRINCOMP), clustering (CLUSTER), discriminant (DISCRIM), step-bystep (STEPDISC) and canonical (CANDISC) analyses, using the Statistical Analysis System (SAS®). A multiple analysis of variance (MANOVA) was carried out with the variables defined as important by the discriminant analysis. The principal components analysis for biometric characteristics and scrotum-testicle, for physiological characteristics and body temperature as well as the characteristics of the skin and hair explained 60, 70 and 67 % of the total variation, respectively. The dendrogram showed a clear separation between the breeds studied and the existence of two distinct groups, one formed by the Texel and the other by the other breeds, considering all the characteristics used in the study. The most useful morphological parameters to explain heat tolerance were diameter of hair, layer thickness of hair at withers, 12th thoracic vertebra and rump, withers height, thoracic and scrotal circumferences, body weight, anterior and posterior shin perimeters, hair and epidermis brightness as well as the content of red and yellow in the epidermis. Among physiological characteristics, respiratory rate was better than rectal temperature and heart rate to explain changes caused by thermal stress. From the multivariate and variance analyzes it can be concluded that the Santa Ines breed was the most tolerant to heat stress as it presented a highly pigmented epidermis, a shorter hair of larger diameter, the lower layer thickness of hair at withers, 12th thoracic vertebra and rump, the lower temperatures in the testicle and at the 12th thoracic vertebra as well as the lower respiratory rate and rectal temperature value.

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Photoperiodicity in cattle. I. Seasonal changes in coat character and their importance in heat regulation

Cited by 69 publications

References 0 publications

Skin and coat traits in sheep in Brazil and their relation with heat tolerance

Skin and coat traits in sheep in Brazil and their relation with heat tolerance

Heat stress in cattle and the effect of shade on production and behaviour: a review

Breed comparison for heat adaptation in rams using multivariate analysis

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