Differences of skin morphology in Bos indicus, Bos taurus, and their crossbreds.

Cutaneous evaporation is the main avenue by which cattle dissipate heat via the involvement of sweat glands and other skin components. The difference in skin morphology between B. indicus and B. taurus has been recognized, as well as differences in their ability to tolerate heat. The objective of this study was to compare skin morphology between B. indicus, B. taurus, and their crossbreds. Skin samples of Sahiwal (B. indicus) (n=10, reddish brown skin) and Holstein Friesian (HF) (B. taurus) (n=10, black and white skin) and crossbred of HF75% (n=10, black and white skin) and HF87.5 % (n=10, black and white skin) were biopsied for histological study, followed by measurement of skin components. The results indicated that breed significantly affected sweat gland morphology. The shape of the sweat gland, as indicated by the ratio of length/diameter, in Sahiwal was baggier in shape compared to HF (5.99 and 9.52) while values for crossbreds were intermediate (7.82, 8.45). The density and volume of sweat glands in Sahiwal (1,058 glands/cm(2); 1.60 µ(3) × 10(-6)) were higher than in HF (920 glands/cm(2); 0.51 µ(3)x10(-6)) and crossbreds, both HF 75 % (709 glands/cm(2); 0.68 µ(3) × 10(-6)) and HF 87.5 % (691 glands/cm(2); 0.61 µ(3) × 10(-6)) respectively. However, capillary surface area was greater for HF (2.07 cm(2)) compared to Sahiwal (1.79 cm(2)); accordingly, the lower genetic fraction of HF in crossbred cattle showed less capillary surface area (1.83 and 1.9 cm(2) for HF75% and HF87.5 %) (P<0.01). Nerve density was not significantly different between Sahiwal and HF but was higher in the crossbred (P<0.01) cattle. Moreover, the effect of skin color (black and white) was evaluated and it was found that there was an interaction (P<0.01) between breed and skin color on the skin components. This study reveals that there are differences in skin morphology among B. indicus, B. taurus and their crossbreds, with these differences being more or less related to the genetic fraction of HF. This may imply that capability for cutaneous evaporative heat loss and tolerance to heat in crossbred cattle could be related to skin morphology.

The effects of high temperature and roof modification on physiological responses of swamp buffalo (Bubalus bubalis) in the tropics.

The objective of the experiments reported here was to measure the effects of cooling techniques (Modified roof vs Normal roof) on the performance and physiology of 12 young male buffaloes with a similar live weight of 160 kg. The study was conducted at Chainat Agriculture and Technology College, Chainat Province, Thailand. The animals were divided randomly into two groups, each group comprising six buffaloes, and the two groups were studied to evaluate the effects of modified roofing (normal roof fitted with woven polypropylene shade cloth) on the subjects' physiological responses to heat stress under hot humid conditions. The modified roof resulted in lowered heat stress in buffaloes compared to those under a standard roof. The difference was shown by the buffaloes having a significantly lower mean rectal temperature (39.14 ± 0.07 vs 40.00 ± 0.10°C) and plasma cortisol (2.14 ± 0.24 vs 3.38 ± 0.37 ng/ml). The average daily water consumption was significantly lower in the MR group (MR, 29.71 ± 0.86 vs NR, 34.14 ± 1.06 L head (-1) day(-1)), while there was a tendency for the roughage intake to be higher in the MR group compared to that of the NR group (MR, 5.88 ± 0.18 vs NR, 6.44 ± 0.19 kg head-1 (-1) day(-1); P = 0.0508). It was concluded that roof modification facilitated a reduction in heat load from roof re-radiation, and was an effective means of alleviating thermal stress in young buffaloes.

Productivity of Thai Brahman and Simmental-Brahman crossbred (Kabinburi) cattle in central Thailand.

The productivity of the new crossbred cattle Kabinburi (K) was compared to that of Thai Brahman (TB) using 756 production records from K cattle and 1,316 production records from TB cattle kept at three locations in Thailand. The data were analyzed for the effect of breeds and locations. The ambient temperature, the humidity, the Temperature-Humidity Index (THI) and the rainfall of the three locations were different. Lamphayaklang Livestock Research and Breeding Center (LP) had the highest rainfall/year followed by Nongkwang Livestock Research and Breeding Center (NK), and Prachinburi Livestock Breeding Station (PC). Kabinburi cattle had a higher bodyweight at birth as well as at 200, 400 and 600 days of age than TB cattle. Furthermore, K heifers gave birth to their first calf at a younger age and had a shorter calving interval than TB cows. Thai Brahman cattle kept at LP had significantly higher bodyweight at 400 and 600 days than the animals kept at NK, but bodyweight at birth and 600 days of age were not significantly different. Thai Brahman cattle kept at LP were younger at first calving and had a shorter calving interval than the animals kept at NK. K cattle kept at NK were heavier at birth and at 200, 400 and 600 days of age than the animals kept at PC. Furthermore, Kabinburi cows kept at NK were younger at first calving (P<0.01), but the calving interval was not different between the two groups kept at NK or PC.

Blood biochemical profiles of thai indigenous and Simmental x Brahman crossbred cattle in the Central Thailand.

Plasma biochemical profiles were studied in 112 mature (3 to 5-year-old) healthy cattle comprised of 61 Thai indigenous and 51 Simmental x Brahman crossbred male and cyclic female cattle at Nongkwang (Central Thailand) Livestock Research and Breeding Center, Thailand. Data were analysed for the effect of breed and sex. The results showed that the plasma glucose and gamma-glutamyl transferase (GGT) in the two breeds were significantly (P < 0.05) different. Furthermore, the urea, creatinine, albumin, total protein, aspartate amino transferase (AST), alanine amino transferase (ALT) and alkaline phosphatase (ALP) levels in Thai indigenous were significantly (P < 0.01) higher than in crossbred cattle. However, creatine kinase did not significantly differ in crossbred and indigenous animals. A sex difference was found in glucose level with male Thai indigenous having significantly higher levels (P < 0.05) than the other three groups. Plasma urea concentration in male crossbred cattle was lower than in the other groups (P < 0.05). Female crossbred cattle had significantly (P < 0.05) lower plasma creatinine levels than the other animals. Furthermore, levels of albumin in male and total protein in female crossbred were the lowest (P < 0.05) among the groups. The AST, ALT, ALP and GGT levels were significantly (P < 0.05) different between male and female. Female crossbred cattle had the lowest (P < 0.05) AST and GGT levels, whereas lowest (P < 0.05) ALT and ALP concentration was determined in male individuals of these breeds.

Effects of evaporative cooling on reproductive performance and milk production of dairy cows in hot wet conditions.

Fourteen animals of second and third lactation of Thai Friesian crossbred cows (87.5% Friesian x 12.5% Bos indicus) located at Sakol Nakhon Research and Breeding Centre, Department of Livestock Development, Ministry of Agriculture and Cooperatives, were divided randomly into two groups of seven each to evaluate the effects of evaporative cooling on reproductive and physiological traits under hot, humid conditions. Results indicated that installation of evaporating cooling in the open shed gave a further improvement in ameliorating heat stress in dairy cows in hot-wet environments by utilising the low humidity conditions that naturally occur during the day. The cows housed in an evaporatively cooled environment had both a rectal temperature and respiration rate (39.09 degrees C, 61.39 breaths/min, respectively) significantly lower than that of the non-cooled cows (41.21 degrees C; 86.87 breaths/min). The former group also had higher milk yield and more efficient reproductive performance (pregnancy rate and reduced days open) than the latter group. It is suggested that the non-evaporatively cooled cows did not gain benefit from the naturally lower heat stress during night time.

Analysis of climatic risk for cattle and buffalo production in northeast Thailand.

A study of thermal stress risk for cattle and buffalo was made in the Northeast Region of Thailand. Three-hourly air and dew-point temperatures from 15 selected meteorological stations for the period 1990 to 1999 were used to compute values of the temperature/humidity index (THI). Maps of isolines of THI values were generated by geographical software. A THI > or = 84 was assumed to represent conditions where production losses would be likely to occur. Across the study area, the mean total number of days with THI > or = 84 was 56. However, there was a strong north to south gradient across the region. The results suggest that the highest risk of loss to production in the cattle and buffalo industries is in the southern part of this region.