S.G. Coelho

Parâmetros fisiológicos de bovinos cruzados submetidos ao estresse calórico

The thermoregulation physiological responses in thermoneutrality and heat stress of crossbred calves (½Gir x ½Holstein), males and females, with age between 14 and 20 months were studied. The animals were submitted to thermoneutrality (22°C and 70% of relative humidity) and to heat stress (42oC and 60% of relative humidity) in summer and winter seasons in bioclimatic chamber. Rectal temperature (TR), respiratory rate (FR) and body surface temperature (BST) were registered at 6 AM and 4 PM. It was observed increase in TR, FR and BST in the heat stress period (P 0.05) was observed for BST.

Effects of milk replacer feeding strategies on performance, ruminal development, and metabolism of dairy calves

Performance, rumen development, and metabolism of male Holstein calves (n=54) were evaluated according to 1 of 3 liquid feeding strategies: 4 L of milk replacer (MR)/d until 60 d old (4 L-60 d), 6L of MR/d until 29 d old and 4 L/d from 30 to 60 d (6L-29 d/4 L-60 d), or 6L of MR/day until 60 d old (60 d-6L). Water and starter were provided ad libitum. Intakes of MR and starter were monitored daily and body weight (BW) weekly. Blood samples for glucose and insulin concentrations and ruminal content samples for volatile fatty acids and ruminal ammonia concentrations were collected at 15, 30, 45, 60, 75, and 90 d of age. Six calves on each treatment were euthanized at 30, 60, and 90 d of age. Empty weights of forestomach and abomasum, papillae length, and mitotic index were measured. Average MR intake/d (expressed as a percent of BW) was greater for calves receiving 6L/d than for those receiving 4 L/d until 30 d of age. Calves on the 6 L-29 d/4 L-60 d had the smallest MR intake from 30 to 60 d old, followed by the 4 L-60 d and 6L-60 d treatments. Starter intake (kg of dry matter/day) did not differ between groups. It increased from 0.065 kg/d in the first month to 0.386 kg/d in the second month, and to 2.065 kg/d after weaning. Weight gain was greater for calves fed more MR in the first month, but no difference was observed during the second month. After weaning, 6L-60 d calves had greater rate of weight gain than others and were heavier at 30, 60, and 90 d of age. Weight of empty forestomachs, ruminal pH, and ammoniac nitrogen concentration were not different among groups. Propionate concentration was lower for 6 L-60 d calves, but acetate and butyrate concentrations were not influenced by MR feeding strategy. Calves fed more MR until d 30 had greater ruminal epithelium mitotic index. The different MR feeding strategies did not influence papillae length or ruminal epithelium thickness. Lesions such as ruminal parakeratosis or hyperkeratosis were not observed. The MR feeding strategy did not affect glucose concentration, but insulin was higher in 6L-60 d calves than in the other groups. Glucose concentration increased with age, whereas insulin decreased until 45 d old, and then started to increase until 90 d. In conclusion, MR feeding strategy did not influence ruminal development. Feeding calves 6 L of MR/d over 60 d resulted in greater rate of weight gain without negative effects on starter intake or forestomach development. The weight advantage that 6L-60 d calves obtained preweaning was maintained until 90 d of age.

Desempenho de bezerros alimentados com dietas líquidas à base de leite integral ou soro de leite

Quinze bezerros da raca Holandesa, desaleitados aos 30 dias de idade, foram utilizados para avaliar os efeitos da inclusao de fontes proteicas alternativas, em substituicao as proteinas do leite integral, na formulacao de sucedâneos do leite. Os animais foram divididos em tres grupos: o grupo controle (C) - recebeu leite em po integral reconstituido; o grupo sucedâneo SL (soro/leite) recebeu 41,6% da proteina bruta (PB) vinda do concentrado proteico de soro (CPS), 23,1% do soro de leite e 35,3% do leite em po integral; e o grupo sucedâneo S (soro) recebeu 68% da PB vinda do CPS e 32% do soro de leite. O consumo de concentrado, feno, sal mineral e agua foi mensurado diariamente, enquanto o ganho de peso foi avaliado semanalmente. Nao houve diferenca (P>0,05) para o consumo de concentrado, sal mineral e agua entre os grupos, nos periodos avaliados. O consumo de feno e o ganho de peso foram inferiores nos animais do grupo S (P<0,05). A substituicao de 100% do leite integral por CPS e soro de leite influenciou negativamente o desempenho.

Efeito da substituição do feno de Tifton 85 pelo caroço de algodão como fonte de fibra na dieta de bezerros

Para avaliar a substituicao do feno Tifton 85 pelo caroco de algodao como fonte de fibra na dieta foram utilizados 24 bezerros da raca Holandesa, distribuidos em dois grupos. O grupo-feno recebeu feno e concentrado separados, fornecidos a vontade, e o grupo- algodao recebeu caroco de algodao incorporado ao concentrado (13,5%), a vontade. O consumo de alimentos, o peso, as alturas da cernelha e do ileo, as circunferencias toracica e abdominal, a concentracao de glicose sanguinea, as concentracoes de acetato, propionato e butirato, o pH do fluido ruminal e os pesos dos compartimentos do estomago foram mensurados. O consumo de alimentos, o desenvolvimento ponderal dos animais, as concentracoes de acetato, propionato e butirato, o pH do fluido ruminal, as concentracoes de glicose sanguineas e o peso dos compartimentos do estomago foram semelhantes entre os tratamentos (P>0,05). A necropsia, nao foram observadas alteracoes sugestivas de intoxicacao por gossipol. Concluiu-se que o caroco de algodao substituiu, sem prejuizos, o feno como fonte de fibra na dieta de bezerros.

Technical note: Validation of a system for monitoring individual feeding behavior and individual feed intake in dairy cattle

The objective of this study was to validate an electronic system for monitoring individual feeding behavior and feed intake (Intergado Ltd., Contagem, Minas Gerais, Brazil) in freestall-housed dairy cattle. No data have been published that validate either the behavioral measurement or the feed intake of this system. Feeding behavior data were recorded for 12 Holstein cows over 5d using an Intergado system and time-lapse video. The cows were fitted with an ear tag containing a unique passive transponder and provided free access to 12 feed bins. The system documented the visit duration and feed intake by recording the animal identification number, bin number, initial and final times, and the difference between feed weight at start and end of each feed bin visit. These data were exported to Intergado web software and reports were generated. Electronic data on animal behavior were compared with video data collected during the same evaluation period. An external scale was used to manually measure and validate the electronic systems ability to monitor dairy cow feed intake for each feed bin visit. The feed intake was manually measured for 4-h time periods and compared with the sum of the feed intake recorded by the monitoring system for each cow visit during the same time period. Video and manual weight data were regressed on the electronic feeding behavior and feeding intake data to evaluate the precision of the monitoring system. The Intergado system presented high values for specificity (99.9%) and sensitivity (99.6%) for cow detection. The visit duration and feed intake per visit collected using the electronic monitoring system were similar to the video and manual weighing data, respectively. The difference between the feed intake measured manually and the sum of the electronically recorded feed intake was less than 250g (25,635±2,428 and 25,391±2,428g estimated using manual weighing and the electronic system, respectively). In conclusion, the Intergado system is a reasonable tool to monitor feeding behavior and feed intake for freestall-housed dairy cows.

Avaliação da incidência e fatores de risco da retenção de placenta em vacas mestiças leiteiras

The incidence rate, risk factors and impact of retained placenta on the reproductive and productive performance of crossbred dairy cows was evaluated. The frequency distribution of retained placenta and also a Poisson multivariate analysis were developed for the following variables: year, calving season, lactation order, body condition score, gestation length, type of delivery, number and sex of calves. First calf heifers and multiparous cows, with and without retained placenta, during the rainy and dry season, had their average results compared in the following items: days from calving to first service, number of semen doses per conception, milk production up to 305 days and lactation peak. The incidence rate of retained placenta was 12.8%. The risk factors were: rainy calving season, 2nd, 3rd and above 4th lactation orders, body scores below 3.5 and greater than 4.0, abortion, stillbirth, premature birth, assisted birth and multiple birth. An increase of 51.2 and 27.5 days in the average interval between calving and first service, and of 1.2 and 0.6 in the average number of semen doses was observed in multiparous cows with retained placenta, giving birth during the rainy and dry seasons, respectively (P<0.05).

Produção e composição do leite de vacas alimentadas com dietas com diferentes proporções de forragem e teores de lipídeos

Milk yield and composition of Holstein dairy cows fed different forage to concentrate ratio as well as different lipid contents in the diets were studied. Eight cows with 58±9 days in milk and average production of 28±4 kg/day were assigned in a double Latin square design 4 x 4, in a 2 x 2 factorial arrangement. Treatments were diets with high forage and low lipid levels, high forage and high lipid levels, low forage and low lipid levels and low forage and high lipid levels. Milk yield and fat corrected milk yield (3.5%) were not affected by treatments (P>0.05). The reduction on forage ratio in the diet decreased milk fat percentage and production (P<0.05). The increase in lipid levels in the diets reduced total milk solids as well as milk urea nitrogen concentrations (P<0.05).

Environmental and genetic effects on the lactation curves of four genetic groups of crossbred Holstein-Zebu cows

The objective of this study was to evaluate the effects of genetic group and environmental factors, including farm of origin, season of calving and lactation number, on the individual lactation curves of 1,010 Holstein-Gyr, Guzerat-Holstein, Holstein-Nellore, and Holstein-Zebu F1 cows on the experimental farms of the Agricultural Research Company in Minas Gerais (Empresa de Pesquisa Agropecuaria de Minas Gerais, EPAMIG). Least squares analysis and the incomplete gamma function were used to investigate differences in early milk yield, peak milk yield, time from onset to the lactation peak, persistency, total milk yield and lactation duration. The highest early yields were observed for Holstein-Gyr and Holstein-Zebu, and the lowest were observed for Holstein-Nellore cows. Early yield increased with lactation number, and the lactations that began in the late rainy and early dry seasons had the highest early yield. The time between lactation onset and the lactation peak was longer for primiparous Holstein-Gyr and Holstein-Guzerat cows. The lowest yields at the lactation peak were observed for the first lactation number. The highest values of persistency were observed for the first lactation number in Holstein-Guzerat cows. Total production from Holstein-Gyr and Holstein-Zebu cows were higher by approximately 14% and 29% compared with Holstein-Guzerat and Holstein-Nellore cows, respectively. The highest total yields were observed in lactations beginning in the dry season. Total yield increased with lactation number. The shortest lactation periods were observed in lactations beginning late in the rainy season. The incomplete gamma function was used to fit the individual curves from the genetic groups evaluated. The total yield differences were linked to early yields and yields at the peak of lactation.

Silagens de girassol e de milho em dietas de vacas leiteiras: consumo e digestibilidade aparente

The intake and the apparent digestibility of dry matter, organic matter, neutral detergent fiber, acid detergent fiber and the intake of crude protein were evaluated in lactating Holstein cows fed sunflower silage (SS) in replacement of corn silage (CS) in their diets. Five ruminal cannulated cows, 60 to 82 days in milk, were arranged in a 5 x 5 latin square design. The treatments werethe following: 100% corn silage (100CS) and concentrate; 34% sunflower silage plus 66% corn silage (34SS) and concentrate; 66% sunflower silage plus 34% corn silage (66SS) and concentrate; 100% sunflower silage (100SS) and concentrate;and 100% corn silage plus whole cotton seed (CS-WCS) and concentrate. Dry matter (17.86kg for 100SS and 21.62kg for 100CS) and organic matter intake (17.5kg for 100SS and 20.2kg for 100CS), intake and apparent digestibility of neutral detergent fiber and acid detergent fiber were lower for 100SS compared to 100CS (P<0.05). Apparent digestibility of organic matter for treatment 100SS was the lowest (54.8%). Increasing levels of corn silage in the diets increased the dry matter intake, the organic matter intake and the apparent digestibility. Parcial replacement of the corn silage with sunflower silage could be a viable option for lactating cows diets.

Desempenho de bezerros alimentados com silagem de leite de transição

O objetivo deste trabalho foi avaliar o desempenho de bezerros da raca Holandesa, aleitados com leite ou silagem de leite de transicao diluida em agua ou misturada ao leite, bem como realizar analise economica das dietas. Foram utilizados 18 animais, com peso corporal inicial medio de 36,50±4,03 kg, alojados individualmente em baias. Os animais receberam quatro litros de dieta liquida por dia, durante 54 dias. Os dados de consumo, ganho de peso diario, medidas de crescimento e conversao alimentar foram analisados em parcelas subdivididas; e o peso corporal final, o ganho total e a ocorrencia de diarreia foram analisados em delineamento inteiramente casualizado. A silagem de leite de transicao nao alterou o consumo de concentrado e o total de materia seca, nem a ocorrencia de diarreia. O desempenho dos animais foi reduzido, quando a silagem foi diluida em agua, o que resultou em menor peso final e menor ganho total de peso. Os animais tratados com silagem misturada ao leite tiveram desempenho similar aos tratados com leite, o que possibilita menor custo por quilograma de ganho de peso total e se mostra como opcao viavel para o aleitamento de bezerros leiteiros.