Transfer of Thai Native Cattle Feeding Technology to Cattle Farmers in Rural Communities in Sakon Nakhon Province, Thailand, in Response to Global Warming to Produce Cattle with the Characteristics of Physiological Adaptability, Heat Tolerance and Increased Production Performance

MATERIALS AND METHODS

Sixteen castrated male TN cattle that had similar body weights, body condition scores and a similar genetic balance were evaluated in a preliminary experimental period of 2 weeks for their body adjustments and were then allocated in a randomized complete block design (RCBD). During this period, all cattle were arranged to obtain the factors of interest. Blood samples were collected to analyze the hematological values, namely, hematocrit (Hct), hemoglobin (Hb), blood glucose (BG) and blood urea nitrogen (BUN). Four experimental concentrate feed formulas with 12% protein and 72% total digestible nutrients (TDN) were used as follows: (1) Control concentrate feed with 3% minerals, (2) 15% PSM concentrate, (3) 15% PKSM meal concentrate and (4) 15% CSM concentrate. The experimental roughage used was rice straw and cattle mineral blocks from the Department of Livestock Development were used for free choice licking. The cattle houses in this study belonged to local farmers and were covered with a single-slope shed roof of zinc mixed-metal sheets with no ceiling. They were open houses under the normal climatic conditions and normal ventilation. Inside the houses, they were divided into individual lots with individual waterers and feeders.

Data were collected on the meteorological factors and general physiological changes, the respiration rate, rectal temperature and pulse rate⁴, heat tolerance coefficient⁵, sweating rate⁶, hematological values were obtained by the micro-hematocrit method, the hemoglobin levels were obtained by the acid hematin method⁷ and the cortisol levels were obtained by the RIA method using the Amerlex Cortisol RIA Kit Code IM. 2021 Kodak Clinical Diagnostics Ltd., Amersham UK⁸. Data on the production performance of experimental cattle were collected, such as the weights of concentrate and roughage intake and the body weights of the cattle. Analysis of concentrate and roughage quality, such as dry matter, crude protein, lipid, ash, calcium and phosphorous, was conducted⁹. Analysis of roughage for the percentage of acid detergent fiber (ADF) and neutral detergent fiber (NDF)¹⁰ was also performed.

The data were analyzed for the relation between the meteorological factors and general physiological changes in the experimental cattle through polynomial regression analysis and an analysis of variance of general physiological changes and cattle production performance¹¹ was also performed. The differences between the means of studied factors were compared using least squares means. Analysis of animal welfare and behavior of TN cattle was performed using assessment tools that had been developed by the researchers in this study.

The locations, houses and TN cattle evaluated in this experiment belonged to the local farmers. Analyses of hematological values (hematocrit, hemoglobin, blood glucose, blood urea nitrogen and cortisol levels) were conducted at the Department of Animal Science, Faculty of Agricultural Technology, Sakon Nakhon Rajabhat University. Analysis of the composition of cattle feeds was done at the Department of Animal Husbandry, Faculty of Agriculture, Kasetsart University (Bangkhen campus, Bangkok) and at the Science Center of Sakon Nakhon Rajabhat University. This experiment started in October, 2008 and ended in September, 2009.

RESULTS

The result showed that the housing characteristics influenced the inside environment surrounding the cattle. The observed value for the temperature humidity index (THI) was 88.74±3.46 and it was affected by ambient temperature environments (Table 1). The analysis of the relation between THI and ambient temperature showed a significant difference (p<0.01) (Table 2), additionally, the influence of solar radiation on TN cattle housing affected the ambient temperature environments, which showed a THI of 80.03±2.48 (Table 3). From polynomial regression analysis, the relation between the ambient environmental values for THI and general physiological changes of experimental cattle was significantly different (p>0.05) (Table 4).

The experimental cattle fed different concentrates for treatments 1, 2, 3 and 4 showed general physiological changes, heat tolerance coefficients, sweating rates and drinking water volumes that were not significantly different (p>0.05) (Table 4). The animal welfare and behavior of the experimental cattle was not significantly different (p>0.05) (Table 5) and there was no effect on the hematological values (Hct, HG), cortisol concentrations and blood urea nitrogen (BUN) levels, which were not significantly different (p>0.05) (Table 6-10).

Comparison of nutrient compositions among experimental feeds of treatments 1, 2, 3 and 4 including nutrient composition in roughage was found that they were not significantly different (p>0.05) (Table 11 and 12). Analysis of effect of experimental feed (concentrate and roughage) on production performance (final body weight, gain in weight and ADG) of TN cattle was not significantly different (p>0.05) (Table 13).

Table 1:	Factors of ambient temperature environments affecting environmental conditions during the experimental session
*Temperature which was measured from the middle of brass bulb of thermometer that sprayed with black color, this figure was temperature and added with heat from solar radiation

Table 2:	Analysis of relation between temperature humidity index (THI) and ambient environment (maximum, average, minimum and different temperatures)
**Means a highly significant difference (p<0.01)

Table 3:	Effects of influence of solar radiation on ambient environments

Table 4:	Means of general physiological items of TNC in each feed formula
Means within the same row did not differ significantly (p>0.05)

Table 5:	Means of animal welfares and behaviors of Thai native cattle in this experiment
Means within the same row with different superscript differed significantly (p<0.05), INTPN: Interpretation, MOD.: Moderate

Table 6:	Means of hematocrit of experimental cattle in preliminary-experiment, during experiment, post-experiment and whole period of this experiment
Means within the same column did not differ significantly (p>0.05)

Table 7:	Means of hemoglobin of experimental cattle in preliminary-experiment, during experiment, post-experiment and whole period of this experiment
Means within the same column did not differ significantly (p>0.05)

Table 8:	Means of cortisol hormone concentration in preliminary-experiment, during experiment, post-experiment and whole period of this experiment
Means within the same column did not differ significantly (p>0.05)

Table 9:	Means of blood glucose concentration in preliminary-experiment, during experiment, post-experiment and whole period of this experiment
Means within the same column did not differ significantly (p>0.05)

Table 10:	Means of blood urea nitrogen concentration in preliminary-experiment, during experiment, post-experiment and whole period of this experiment
Means within the same column did not differ significantly (p>0.05)

Table 11:	Composition of experimental feed (concentrate) in each treatment
Means within the same row did not differ significantly (p>0.05)

Table 12:	Composition of experimental feed (roughage)

Table13:	Production performance of TNC
Means within the same row did not differ significantly (p>0.05)

DISCUSSION

TN cattle have developed and adapted through evolution in the tropical zone. Therefore, they have become wrinkled and have evolved big ears, such as Zebu cattle (Bos taurus indicus). Their wrinkly skin, which increases the skin surface area can dissipate body heat to maintain a normal body temperature and can alleviate heat stress better than tight skin. According to the theory of heat transfer, a wide surface area can ventilate heat more effectively than can a narrow surface area in the same period of time, regardless of whether the heat is convention.

Stefan’s law of radiation states that the rate of heat transfer by radiation from the body to the surroundings is related to the energy density of the radiation in a volume of space. Additionally, the increase in body temperature will depend on the temperature of the surroundings. The body both emits and absorbs radiation from its surroundings. Newton’s law of cooling states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and surroundings. One interesting fact about algebra claims that the change in surface area is equivalent to the power square of 2/3 of the body weight for a similar body shape and the same gravity¹². However, animals of the same bred might have different body shapes and different gravities¹³. Under high ambient temperature, TN cattle reduced feed intake, but the quantity and weight of feed intake were still higher than those of European cattle (Bos taurus). Zebu cattle had higher critical temperatures, whereas, European cattle had lower ones. The upper critical temperature in Zebu cattle then had a greater influence on the body’s thermoregulation and low temperature than did the lower critical temperature in European cattle^14,15. The efficiency of growth was determined as the ratio of tissue production to metabolism and was expressed as energy. The difference between the two values of energy appeared to become heat energy¹⁶. The heat energy balance was an effective factor that caused the close relation between thermoregulation and the growth rate. Thus, TN cattle under heat stress would be affected by general physiological changes, hematological value changes and the function of endocrine glands that reduce roughage intake¹⁷. Animal bodies require energy for transferring body heat to the surroundings, which can lead to general physiological changes, hematological mechanisms and endocrine gland functions in response to normal body temperature regulation. That is why heat affects animal lipid metabolism.

The study found that TN cattle under local normal housing conditions showed changes in their general physiology, such as a higher rectal temperature, higher pulse rate, higher respiration rate and higher sweating rate, which is their mechanism for maintaining a higher balance of normal body temperature by transferring heat to cooling evaporation¹⁸. More energy is usually needed to make this process work. The study also revealed that TN cattle faced heat stress, which impacted the energy available for maintaining life¹², thereby reducing the hematocrit and hemoglobin levels¹⁹. Due to the animal thermoregulatory processes of sweat expulsion and evaporation, TN cattle unavoidably needed more water consumption²⁰. The plasma level was thus increased, which increased the number of broken red blood cells and thereby reduced the hematocrit and hemoglobin levels²¹. This finding was congruent with the study of Umpapol et al.¹⁸, who revealed that beef cattle raised in single-roof houses had lower hematocrit and hemoglobin levels than did those raised in double-roof houses.

The body heat production of TN cattle under a high ambient temperature for a long time decreased due to their low food intake and low net energy, which was caused by high ambient temperature environment, which directly impacted the function of the hypothalamus and the anterior pituitary gland²² and increased the secretion of cortisol from the adrenal cortex. However as the cattle were under continuous heat stress for a long time, the cortisol concentration declined²³. The mechanism of body adjustment might decrease the body heat production from food metabolism due to excess cortisol, to an adjustment of cortisol metabolism that suppresses the function of 17-Hydroxylase in the adrenal cortex or to a threshold sensitivity evaluation or set point sensitivity evaluation of the adrenal cortex²⁴.

At this point, it was revealed that TN cattle had faced heat stress throughout the experimental period with high THI, which caused the decline of the heat tolerance coefficient²⁵ and affected the functions of the endocrine glands, especially the increase in cortisol levels, which decreased the body heat production due to a food intake reduction²⁶. Later, the cattle’s bodies could decrease their cortisol levels to the body heat balance level. The TN cattle could finally self-adjust well to the normal body temperature level because they had a positive characteristic of high heat tolerance²⁷.

The influence of high air temperature and high relative humidity could cause heat stress in TN cattle but their bodies had general physiological changes for reducing such stress by ventilating heat out of their bodies. This ventilation was accomplished through respiratory regulation centered in the hypothalamus, which was sensitive to blood temperature changes. When the blood temperature increased, this respiratory regulation center would increase the rate of cattle respiration for heat evaporation²⁸ and body thermoregulation²⁴. The TN cattle under a high ambient temperature that faced heat stress could increase their body heat via the fermentation of fiber in the rumen³.

An increasing body heat can exhaust the cattle with normal body temperature regulation and these cattle reduce their rumination activities to keep their body heat balanced²⁹. TN cattle under high ambient temperature drink much more water for body heat regulation and water which has a high specific heat value can accommodate more temperature changes by not allowing a rapid body temperature alteration³⁰. Usually, the volume of water used in sweat expulsion is an efficient mechanism of cattle body heat transfer. At the same time, the cattle tried to perform gasping respiration to regulate their body heat, although it was not an efficient way for them to adjust their normal body temperature balance without any water consumption. Therefore, they required a large amount of water for normal body temperature regulation³¹, which was normally accompanied by frequent standing up and walking to drink water in high-ambient-temperature environments.

TN cattle housed in high-ambient-temperature environments had general physiological changes that caused gasping respiration as well as muscle and diaphragm function that required more metabolizable energy from lipid metabolism of ingested food³². If the cattle bodies had less metabolizable energy, this could affect production performance, such as growth and carcass quality³. TN cattle must adapt themselves to high ambient temperatures by reducing body movements, keeping still for rest and lying³¹ to reduce the utilization of energy for body maintenance³³.

The situation of heat stress was related to a low heat tolerance co-efficient that was derived from the impact of endocrine gland functions, in particular, the cortisol hormone level was increased³⁴ to maintain a normal body heat balance by reducing the food intake to regulate the body to such an extent that the cortisol hormone level declined and the animal body heat became normal. This adjustment function of TN cattle required energy to maintain life by reducing both the average daily gain²⁵ and the feed digestibility of the cattle. Therefore, the high-ambient-temperature environment was one factor that stimulated the cattle bodies to regulate a normal body temperature by reducing their feed intake, which is useful for animals under heat stress. Although they relied on energy for thermoregulation, the hormone level changes among the TN cattle could also affect their growth performance. The results of using PSM, PKSM and CSM supplements in feed formulas as good sources of energy that caused changes in the general physiology, hematological values, hormone levels and animal welfare behavior, were not significantly different from the results obtained by using control feed. In addition, all feed formulas were composed of essential nutrients for body growth, namely, protein, vitamins and minerals, which were sufficient for the growth requirements of TN cattle³⁵.

Therefore, the TN cattle that received PSM, PKSM and CSM supplements in feed formulas could improve their efficiency of heat transfer to the extent that they were able to maintain a normal body heat balance efficiently, further, all of the feed formulas could increase energy for TN cattle growth³⁶. The mechanism of body heat balance of the experimental cattle caused them to consume more roughage and obtain enough high energy from the concentrate to provide relief from heat stress. Although the animals obtained more body maintenance energy, especially for the heat transfer process³⁴, they still retained normal body temperatures and increased their net energy for high yield production²⁴. For PSM, PKSM and CSM supplementation in feed formulas, the study revealed that the supplements were sources of high-quality nutrients such as energy, good protein and useful fiber for TN cattle³. The supplementation of PSM, PKSM and CSM at 5, 10 and 15%, respectively, would be beneficial in feed formulas for body thermoregulation, thus increasing the levels of utilizable nutrients for body maintenance the yield production of cattle²³ and leading directly to the improved growth performance and carcass quality of TN cattle²³.

CONCLUSION AND FUTURE RECOMMENDATION

The THI values showed that the ambient temperature was highly related to maximum, average, minimum temperatures and high relative humidity. The data analysis found that THI was high but did not affect general physiological changes in TN cattle.

TN cattle that received 4 different concentrate formulas could tolerate high-ambient-temperature environments and the concentrate formulas had no effect on physiological changes, such as rectal temperature, pulse rate, respiration rate, heat tolerance coefficient, sweating rate and drinking water volumes and the hematological values, namely, hematocrit, hemoglobin, blood glucose, blood urea nitrogen and cortisol levels, including animal welfare behaviors such as rumination, gasping respiration, standing up, walking to drink water, rest and lying down.

TN cattle under high-ambient-temperature environments could be fed well with local feedstuffs such as PSM, PKSM and CSM at 15% in feed formulas and there was no effect on growth performance compared to control concentrate in this experiment.