Evaldo Antonio Lencioni Titto

Respostas fisiológicas e produtivas de vacas holandesas em lactação submetidas a diferentes ambientes

This work was carried out during the summer of 2002 to evaluate the influence of some cooling systems on the milk yield and animal thermoregulation. Ten heifers and seventeen milking cows were assigned to the control housing (ICO), mist & fan housing (ICL) and shade cloth (80%) (IT). The milk yield and the individual intake were daily measured for each animal. The rectal temperature was measured three times a day with three animals from each treatment. The skin surface temperature was collected three times a day for all the animals and the respiratory frequency two times a day for all the animals. The climatic data of each housing were registered to calculate the temperature humidity index (ITU) and the black globe humidity index (ITGU). Twenty six days of high enthalpy were selected and analyzed. The study showed that temperature humidity index from 75 to 76 was not associated with stress conditions for the animals, although many researches propose this situation as stressing. The milking cows in the mist & fan treatment showed respiratory frequency and skin surface temperature significantly lower than the cows in the other treatments. The heifers presented respiratory frequency and rectal temperature higher than the cows in all the registration times. The higher milk yield of the cows was observed in the shade cloth treatment.

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.

Impactos de variáveis climáticas na agilidade de bezerros Nelore neonatos

Com os objetivos de identificar os padroes comportamentais nas relacoes materno-filiais de bovinos da raca Nelore, de entender as interferencias ambientais nesta relacao e de propor solucoes praticas de manejo, foram realizadas medidas de comportamento das atividades de 112 vacas e seus bezerros nas primeiras horas apos o parto, em duas propriedades situadas em Sertaozinho e Brotas, no Estado de Sao Paulo. Foram analisadas as variaveis: tempo para ficar em pe (LP) e tempo para mamar (LM), em minutos, nos bezerros e tempo de contato com a cria (TCC) e tempo deitada (TD), em porcentagem, nas vacas. Foram registradas a temperatura e a umidade relativa do ar para o calculo do indice de temperatura e umidade do ar (ITU), correlacionando-se esse indice com as variaveis comportamentais. Os resultados mostraram efeitos significativos (P<0,05) de propriedade e de local do parto em relacao ao rebanho e ao ITU. A LP pode ser uma medida de vigor em bezerros e mostrou-se influenciada por diversos fatores ambientais. O TCC teve efeito significativo (P<0,05) na LP. A selecao de bovinos de corte deve incluir as caracteristicas de agilidade dos bezerros recem-nascidos e do cuidado maternal das vacas como ferramentas para otimizacao e viabilidade economica dessa exploracao.

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.

Changes in ruminal fermentation and mineral serum level in animals kept in high temperature environments

Para verificar o efeito da temperatura ambiente na fermentacao ruminal do alimento e nas concentracoes de minerais em bovinos em crescimento, foram utilizados 12 bezerros machos (peso medio inicial de 82,9 ± 7,7 kg com 100 dias de idade), durante 38 dias, em delineamento experimental de blocos ao acaso, com medidas repetidas no tempo e duas temperaturas ambiente: ambiente termoneutro (24oC) e ambiente de estresse por calor (33oC). Os animais expostos a temperatura de 33oC tiveram ingestao menor de materia seca, menor nivel serico de T3 (triiodotironina), maior concentracao de nitrogenio amoniacal (NH3-N) no liquido ruminal e maior temperatura retal e corporal em todo o periodo experimental em comparacao aqueles animais mantidos no ambiente termoneutro (24oC). Os animais em ambiente de estresse por calor (33oC) apresentaram maior concentracao de calcio no soro, que foi maior aos 31 dias de experimentacao e menor aos 38 dias. A concentracao de fosforo nesses animais foi menor durante todo o periodo experimental e a de sodio, menor aos 17, 31 e 38 dias de experimentacao. As concentracoes de potassio e zinco foram menores depois de 24 dias; a de cobre menor ate 24 dias; e a de magnesio maior ate 17 dias de experimentacao, todas em comparacao a dos animais mantidos em ambiente termoneutro (24oC). Os animais sob estresse por calor apresentaram maiores concentracoes de nitrogenio amoniacal no liquido ruminal e diminuicao nas concentracoes sericas de fosforo, sodio, potasseio e zinco. Sao necessarias mudancas no manejo alimentar de ruminantes em temperaturas acima do conforto termico, para diminuir as perdas no desempenho.

A device to improve the Schleger and Turner method for sweating rate measurements

The objective of this study was to test a device developed to improve the functionality, accuracy and precision of the original technique for sweating rate measurements proposed by Schleger and Turner [Schleger AV, Turner HG (1965) Aust J Agric Res 16:92–106]. A device was built for this purpose and tested against the original Schleger and Turner technique. Testing was performed by measuring sweating rates in an experiment involving six Mertolenga heifers subjected to four different thermal levels in a climatic chamber. The device exhibited no functional problems and the results obtained with its use were more consistent than with the Schleger and Turner technique. There was no difference in the reproducibility of the two techniques (same accuracy), but measurements performed with the new device had lower repeatability, corresponding to lower variability and, consequently, to higher precision. When utilizing this device, there is no need for physical contact between the operator and the animal to maintain the filter paper discs in position. This has important advantages: the animals stay quieter, and several animals can be evaluated simultaneously. This is a major advantage because it allows more measurements to be taken in a given period of time, increasing the precision of the observations and diminishing the error associated with temporal hiatus (e.g., the solar angle during field studies). The new device has higher functional versatility when taking measurements in large-scale studies (many animals) under field conditions. The results obtained in this study suggest that the technique using the device presented here could represent an advantageous alternative to the original technique described by Schleger and Turner.

Days on feed and sex effects on live weight and carcass traits measured by ultrasound

Existem poucos dados na literatura sobre as alteracoes na composicao corporal de bovinos Nelore e seus cruzamentos, especialmente em relacao a novilhas (NOV) e machos inteiros (MI). A ultra-sonografia e uma ferramenta util para obter essa informacao de forma facil, com minimo disturbio ao animal e a baixo custo. Efeitos do sexo e dias de confinamento sobre o peso vivo (PV) e a area do musculo Longissimus dorsi (AOLU) e a espessura de gordura subcutânea (EGSU) medidas por ultra-som, foram avaliadas em 27 novilhas e 27 machos inteiros, F1 Piemontes ´ Nelore. NOV e MI com PV inicial de 256 ± 5,6 e 265 ± 5,6 kg, respectivamente, foram confinados com uma dieta contendo 77% de NDT, durante 131 dias. O PV, a AOLU e a EGSU foram avaliadas a cada 28 dias aproximadamente. Foi observada uma interacao entre sexo e dias de confinamento para todas as caracteristicas avaliadas. O PV aumentou linearmente com os dias de confinamento e MI apresentaram maior PV que as NOV desde o inicio do experimento. A AOLU media inicial foi 55,8 e 55,5 cm2 nas NOV e MI, respectivamente, aumentando linearmente ate o final do confinamento (78,7 e 82,8 cm2, respectivamente). Em relacao ao efeito do sexo, MI tiveram maior AOLU que NOV somente na ultima medida. A EGSU inicial foi 0,04 e 0,4 mm para MI e NOV, respectivamente e aumentaram linearmente durante e periodo de confinamento (2,4 e 4,3 mm, respectivamente). NOV tiveram maior EGSU desde o inicio ate o final do periodo experimental. MI tiveram maiores taxas de crescimento do PV e AOLU que NOV, no entanto, estas tiveram maior taxa de crescimento da EGSU.

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.

Palatability of Horse Diets Containing Citrus Pulp (Citrus Sinensis) through the Preference Test

The aim of this study was to evaluate the acceptance of concentrates containing increasing levels of citrus pulp (7, 14, 21 and 28%) and the most preferred level of inclusion, observing the first action and the palatability using the preference test. Ten healthy mares, averaging 500 kg live weigh (LW), were housed in individual pens, where the four experimental concentrates were offered simultaneously, in a linear and continuous feeder for horses, for a period of 15 min. During this period, the first action (smelling or eating), the first choice (first concentrate effectively ingested) and the intake ratio (intake of each concentrate in relation to the total concentrate intake) were observed. Effect of inclusion on first action was observed (P<0.01), once 80% of animals fed promptly the concentrate and only 20% smelled it before the choice. The concentrate with 7% of citrus pulp presented the highest intake ratio (0.4425; P<0.01). For the first choice variable, there was no difference (P>0.05), however the concentrate with 7% was the most preferred (36.67%). Citrus pulp can be used as concentrate feed for horses. Therefore, low levels of inclusion in the concentrate, close to 7%, are recommended when the concentrate is based on corn, wheat bran, soybean meal, with no flavour agents like molasses.