Cristiane Gonçalves Titto

Heat tolerance and the effects of shade on the behavior of Simmental bulls on pasture

The objectives were to assess the degree of thermolysis capacity as a characteristic of heat tolerance of the Simmental beef cattle and evaluate the effects of shade and shade type (artificial: AS, trees: TS, or no shade: NS) on daily behavior patterns during summer. Black globe temperature (BGT) was different under the two types of shade (P < 0.05) and was lower under the TS (P < 0.01) and under AS (P > 0.01) than average BGT in the sun. Animals when in AS used more intensely the shade (P = 0.002) mostly lying down under it (10.00-14.00 hours), while time standing was similar (P = 0.107) between TS and NS. Bulls without shade (NS) spent significantly more time at the water trough and most part of the day standing idle (72.4%, 10.1 h/14 h). TS bulls spent more time grazing/standing (P < 0.001). The Simmental bulls that were in TS and AS spent more time ruminating than bulls that stay without shade (NS). The availability of shade changes grazing, rumination and idling behavior of cattle in response to environmental conditions. Shade provided by trees can be more efficient than artificial shading as cattle spent more time grazing when tree shade was available. Thermolysis capacity can be used to select heat-tolerant animals.

Heat stress and ACTH administration on cortisol and insulin-like growth factor I (IGF-I) levels in lactating Holstein cows

ABSTRACT Physiological and productive responses were studied in five Holstein cows in thermal comfort (T1), stress by exogenous adrenocorticotropic hormone (ACTH) administration (T2) and heat stress (T3) to compare acute and punctual stress (ACTH) and prolonged stress (heat stress). During T1 and T2, cows were housed in a climatic-free stall barn. In T3, the animals were kept in a climatic room (air temperature of 37°C from 08:00 to 13:00 h, and of 26°C from 14:00 to 07:00 h) for 7 days. Milk yield, rectal temperature (RT), respiratory rate (RR) and blood samples were obtained before, during and after all treatments. In T1 at 08:00 h, RT and RR were below the upper critical limit. Simultaneously, cortisol and insulin growth-factor I (IGF-I) were within the normal limits. After ACTH administration (T2), cortisol significantly increased, reaching maximum levels at 60 min and returning to basal levels at 300 min. However, IGF-I was not affected. During T3, Holstein cows did not effectively dissipate their body temperature and RT, RR and cortisol significantly increased. There was a 26.6% reduction in milk production after heat stress (P < .05). Prolonged heat stress was more stressful and cows had higher levels of CORT in T3 than in T2 even before the increase in body temperature. Although the total amount of cortisol and IGF-I presented a negative and significant Pearson correlation (r = −0.79), IGF-I was not significantly influenced by heat stress or ACTH administration, and the relationship between IGF-I and heat stress remains controversial.

Evaporative heat loss in Bos taurus: Do different cattle breeds cope with heat stress in the same way?

The aim of this study was to compare two Portuguese (Alentejana and Mertolenga) and two exotic (Frisian and Limousine) cattle breeds in terms of the relationship between the increase in ambient temperature and the responses of the evaporative heat loss pathways and the effects on homeothermy. In the experiment, six heifers of the Alentejana, Frisian, and Mertolenga breeds and four heifers of the Limousine breed were used. The animals were placed in four temperature levels, the first one under thermoneutral conditions and the other ones with increase levels of thermal stress. When submitted to severe heat stress, the Frisian developed high thermal tachypnea (125 mov/min) and moderate sweating rates (117 gm(-2) h(-1)), which did not prevent an increase in the rectal temperature (from 38.4 °C to 40.0 °C). Moderate increases in rectal temperature were observed in the Alentejana (from 38.8 °C to 39.4 °C) and Limousine (from 38.6 °C to 39.4 °C), especially in the period of highest heat stress. The Limousine showed moderate levels of tachypnea (101 mov/min) while showing the lowest sweating rates. The Alentejana showed significant increases in sweating rate (156 gm(-2)h(-1)) that played a major role in homeothermy. The Mertolenga showed a superior stability of body temperature, even in the period of highest heat stress (from 38.5 °C to 39.1 °C). Uncommonly, the maintenance of homeothermy during moderate heat stress was achieved primarily by intense tachypnea (122 mov/min). The sweating rate remained abnormally low under conditions of moderate heat stress, rising significantly (110 gm(-2)h(-1)) without evidence of stabilization, only when tendency for heat storage occurred. This unusual response of the evaporative heat loss pathways infers a different thermoregulatory strategy, suggesting a different adaptation to semi-arid environment and strong association with water metabolism.

Respostas fisiológicas e comportamentais de vacas Holandesas mantidas em sistema adiabático evaporativo

This study aimed to evaluate the influence of cooling systems, ventilation and nebulization on the physiology and behavior of Holstein cows housed in free-stall during the summer of southeastern Brazil. 20 Holstein cows were subjected to two treatments with and without cooling system. Environmental parameters dry bulb temperature, relative humidity and black globe temperature were also recorded. Rectal temperature and respiratory rate were evaluated at 5h, 9h30min, 11h30min, 13h30min, 16h30min, 18h30min e 21h30min. The behavioral variables recorded were posture and activities from 5h to 21:30h. Statistics we done using the method of least squares means. Despite the statistical differences obtained for the physiological variables, they were not biologically effective and indicated that the animals were in thermal comfort. Animals that had ventilation and nebulization have eaten even during the hottest hours of the day. The cooling system is a strategy that allows greater thermal comfort to animals and therefore can optimize milk production by increasing the dietary intake.

Bem-estar durante o período gestacional de ovelhas: uma breve revisão

Nesta revisao, objetiva-se abordar praticas e cuidados relacionados ao bem-estar de ovelhas durante a gestacao em suas fases distintas. O bem-estar tem sido foco de estudos em diversas areas na ovinocultura, mas pouco se tem discutido a respeito de boas praticas durante o periodo gestacional. A gestacao e um ponto-chave para produtividade e rentabilidade da ovinocultura, e os bons cuidados neste periodo podem evitar problemas futuros. Dessa forma, sao abordados aspectos principais do comportamento ovino, pontos relacionados a reproducao, gestacao e relacao materno-filial. Tambem sao discutidos os impactos do estresse pre-natal nas funcoes fisiologicas, neuroendocrinas, reprodutivas e de desempenho dos cordeiros. Estas consideracoes permitirao o melhor entendimento do bem-estar positivo das ovelhas gestantes por meio de aspectos nutricionais, ambientais e de manejo que favorecem a gestacao, o parto e o nascimento de cordeiros saudaveis.

Enriquecimento ambiental e bem-estar na produção animal

Animal welfare is among the main demands of consumers, who are increasingly critical of the quality of life within the environment, which requires the use of static conducts in systems for animal production. From this perspective, the objective of this study was to describe the importance of environmental enrichment in promoting improved welfare in animal production. Environmental enrichment has as main characteristic to reduce stimuli that generate stressful responses and allow the presentation of natural behavior, avoiding the appearance of stereotyped behaviors in confined animals. Natural behavior was defined as the one in which the animal tends to perform freely, by bringing pleasure or promoting good physiological functioning. While animal welfare is related to housing conditions such as bioclimatology and plant biophysics, it can be measured from physiological and behavioral assessments. Stress is seen as a set of intense and prolonged physiological reactions that result in imbalance of homeostasis, with important and irreversible effects on the animals. Thus, it is concluded that the use of environmental enrichment can greatly contribute to the reduction of stressors, improving animal welfare in production systems.

Ethological analysis of piglets with and without teeth worn in the post-nursery phase in commercial breeding

(1)(2) Universidade de Sao Paulo, Faculdade de Zootecnia e Engenharia de Alimentos, Laboratorio de Biometeorologia e Etologia. E-mail giseledelaricci@usp.br, crisgtitto@usp.br (3) Embrapa Suinos e Aves, BR 153. E-mail: osmar.dallacosta@embrapa.br (4) Universidade de Sao Paulo, Faculdade de Medicina Veterinaria e Zootecnia, Departamento de Producao e Nutricao Animal, campus de Pirassununga. E-mail: messiastn@usp.br ___________________________________________________________________________