The objectives of the present study were to evaluate fasting heat Production (FP) and energy metabolism to evaluate comparative maintenance energy requirements for buffalo and cross bred cattle and to compare feeding systems for buffalo and cross bred cattle. Six buffalo and six cross bred cattle of same age group (about two years old) and average live body weight 348 and 240 kg respectively, were taken randomly from the herd for the study. Prior to a 3-4 day fasting period, buffalo and cross bred cattle were offered a mixed diet of wheat straw and concentrates (of varying ratio on dry matter basis) for 21 days. Gas exchanges for each animal and urinary nitrogen excretion were determined for 2 days from day 3rd day of starvation, using open circuit respiration calorimetry. Mean oxygen consumption (1466 l/day and 1278 l/day), carbon dioxide production (1078 l/day and 939 l/day) and methane production nearly zero was obtained for buffaloes and crossbred cattle respectively by using respiration calorimetry. Mean fasting heat production of buffaloes and cross bred cattle were 68.16±0.01 and 74.48±0.90 (Kcal) Kg-1W0.75day-1. Fasting heat production (FHP) found to be significantly (P< 0.05) higher for cross bred cattle than the buffalo group.
In our country both cattle and buffalo are maintained mainly as dairy animals. They play an important role in farmer’s economic life, being an integral part of the farming system and milk production. Despite of many similarities there are some differences also, such as behavioral habits and their interactions with the environment; fermentation processes and anatomical rumen; physiology and capacity of the digestive system. Energy is the most limiting factor for animal productivity. Data on energetics provide valuable information on energy expenditure and consumption (McNab, 2009), comparisons between species (Kabat et al., 2007) and within species including between individuals, genders (Green et al., 2007), breeds (Careau et al., 2010) and genetically altered strains (Kaiyala and Ramsay,2011). Such ‘comparative energetics’ can test hypotheses concerning variation in energy expenditure due to behavioural, physiological, morphological or ecological differences. As metabolic rate is an integrated measure of organism function and it has important consequences for survival and reproductive success (Artacho and Nespolo, 2009). The measurement of whole body energy expenditure (EE) and substrate utilization are monitored by continuous recording of oxygen consumption, carbon dioxide production and when required nitrogen and methane excretion (Frankenfield, 2010). Determination of fasting heat production on non-producing adult animals makes the basis for calculation of minimum quantity of net energy, which must be supplied to the animal to keep it in energy equilibrium. The energy expended in the fasting animal is represented by the fasting heat production. The heat produced by the animal is measured direct Calorimetry or it can be obtained by one of the methods of indirect calorimetry in the open circuit respiration chamber. Basal metabolism is generally defined as the heat production of a completely quiescent animal in a post-absorptive state, within a thermoneutral environment. Although this state can be achieved with human beings, it is extremely difficult to achieve with animals. Consequently, the term “fasting metabolism” has been adopted for animals. Measurement of FHP provides a useful basis of reference for other phases of energy metabolism. In regard to comparative utilization of energy it has been reported that maintenance and production requirements were higher in Murrah buffaloes than in crossbred (Brown Swiss x Sahiwal) cows (Mudgal, 2008).Maintenance energy requirement (Em) for buffalo was 7% lower than that for cattle (Lian and Young, 2005). Metabolisable Energy (ME) feeding standard uses FHP. The heat production is affected by many physical and biological factors besides the description (breed, age, sex, etc.) of animal per se (Chandramoni, 2000).Literature provide very few data on comparative study of fasting heat production in crossbred cattle and buffaloes under the same environmental, physiological and managemental condition. Therefore, the objective of the present study was to use the fasting approach to comparatively evaluate maintenance energy requirements for buffalo and crossbred cattle. Determination of nutritional requirements is the basis of diet formulation and is aimed at increasing the expression of genetic potential and improving feed efficiency. Accurate nutritional requirements would promote productive, economic and environmental viability of animal rearing.
Materials and Methods
Six buffalo and six cross bred cattle of same age group (about two years old) and average live body weight 348 and 240 kg respectively, were taken for the study. Cross bred cattle and buffaloes were put on fasting for three days in the respiratory chamber for assessment of heat production during fasting (at post absorptive stage). Before fasting they fed wheat straw and concentrate in the ratio of 80:20, 50:50 and 20:80 for 21 days, following LCD model. Chemical composition of diet is given in the Table 1.
Table 1: Composition of various TMR diets
|Chemical Composition (%)|
The animal was weighed in morning prior to feeding and watering and kept in respiration chamber for three days for acclimatization and then recording of the respiration data 24 hour for two consecutive days. The animal was provided sufficient amount of clean drinking water during the whole study period inside the respiratory chamber.
Measurement of Respiratory Exchange
Recording of temperature of dry and wet bulb, flow rate, air volume, and atmospheric pressure was done manually at hourly interval. The samples of outgoing air were collected in Douglas bags separately with continuous sampling device. On line CO2, O2 and CH4 content of samples of the outgoing and incoming air from the respiratory chamber was determined. Analysis of CO2, O2 and CH4 was made by Fuzi, Infrared Gas Analyser model Type-ZRJF4C25-BUKLF-GYYVYCY-AZ. The total urine excreted within 24 h was measured and about 100 ml of representative sample was collected in for nitrogen estimation.
The total volume of oxygen consumed by the animal in 24 hr was calculated as per the following formula.
Oxygen Consumed (l/d) =VSTP x difference in the concentration of O2 in in-coming air (%) and outgoing air (%) from the chamber/100
Carbon Dioxide Produced
CO2 produced (l/day) = VSTP x difference in the concentration of oxCO2ygen in in-coming air (%) and outgoing air (%) from the chamber/100
The total volume of methane expired in 24h was calculated by following formula-
CH4 (l) = VSTP X (Mf –Mi ) / 100
where, Mf = Average methane percentage in outgoing air
Mi = Average methane percentage in ingoing air
The heat production was calculated by using data of respiratory (gaseous) exchange and urinary nitrogen excreted (g/day) using Brouwer’s equation (4).
HP= 3.866 (liters O 2) + 1.2 (liters CO2) – 0.229 (U N g × 6.25) – 0.518 (liters CH4)
Respiratory Quotient (RQ) is used as an indicator of in situ energy metabolism (state) of animal and was calculated by dividing volume of CO2 produced (l)/volume of O2 used (l).
The data collected during the experiment was analysed using paired t test using SPSS (1996) computer package.
Results and Discussion
During fasting they were provided clean water similarly as during the respiration chamber study stated earlier. Fasting respiration calorimetric study started when the methane emission stopped or becomes nearly zero. Carbon dioxide production, oxygen consumption and urinary nitrogen excretion was measured for next 24 hours for two consecutive days. Result obtained was presented in Table 2. The total carbon dioxide production (l/day) was significantly higher (P<0.05) in buffalo than cross bred cattle as body size of buffaloes were higher but the CO2 production l/KgW0.75significantly higher (P<0.05) in cattle than buffaloes (Table 2 and Fig. 1).
Table 2: Measurement of Carbon dioxide production, oxygen consumption and urinary nitrogen excretion
|CO2(l)Kg-1W0.75 day-1*||15.65± 0.22a||13.36±0.14b||0.023|
|H P(Mcal )day-1**||4.49±0.12b||5.5±0.27a||0.010|
|HP(Kcal) Kg—1 day-1**||19.57±0.33a||15.77±0.17b||0.008|
|Metabolic Body Weight||60.28||80.68|
*a, b value shows significance difference within the row (P<0.05)
Fig. 1: Fasting carbon dioxide production in Cross bred cattle and buffaloes
The total O2 consumption (l/day) was found to be significantly (P<0.01) higher in buffaloes than cattle. O2 consumption (l)/KgW0.75 was significantly (P<0.01) higher in cattle than buffaloes respectively (Table 2 and Fig. 2). The fasting Methane production was almost zero in both the species. RQ is an index of intermediary metabolism and its values close to 0.7 indicates predominance of fat being utilized as the body fuel. The fasting heat production (Mcal/day) was significantly higher (P<0.01) in buffaloes than cross bred cattle however, the fasting heat production (Kcal/day/KgW0.75) was significantly higher (P<0.05) for cross bred cattle than buffaloes. These results indicate that the basal metabolic rate of buffalo is lesser than cross bred cattle (Table2 and Fig. 3).
|Fig. 2: Fasting oxygen consumption in Cross bred cattles and buffaloes||Fig. 3: Fasting heat production in Cross bred cattles and buffaloes|
The protein turnover rate associated with body growth leads to differences in urinary N excretion (McDonald et al., 1988). Different biological and physical factors affects energy expenditure, differences in reported FHP by various workers may be prominently due to differences in breed, age, sex and physiological status. Regression of fasting heat production on body weight (W) yielded the following equation-
FHP (MJ/kg) = 256.7 W + 13.2, n = 6; r 2= 0.55 and FHP (MJ/kg) = 243.4 W +7.4, n=6 and r2 =0.55
respectively for buffalo and cattle. The positive intercept in the equation indicates that animals utilize endogenous body reserve for maintenance with an associated heat loss.
These variation may occur due lower requirement of metabolisable energy of buffaloes than the cross bred cattle since they are metabolically less active than cattle and their requirements are also low. Due to this difference buffaloes may be better converter of energy than cattle. These results were found to be similar finding as done by Khan (2008) who reported almost similar type of results for fasting heat production as came out in present experiment. Similarly, Qin et al. (2011) reported that fasting heat production and fasting metabolism were linearly and positively related to fasting body weight. These relationships indicate that FHP and FM increased with increasing metabolic fasting body weight (kg0.75).On the contrary Net energy and ME requirement for maintenance (kJ/kg0.75 of live weight) derived from the fasting energy metabolism study for water buffalo are close to those for beef and dairy cattle as proposed in energy feeding systems used in the AFRC (1993).In growing animals protein energy is the main form of energy retention as against the fat in mature animals. The protein synthesis involves turnover of amino acids which causes loss of energy in the form of heat. Fasting heat production is also dependent upon the plane of nutrition before fasting of animal. HP had values 25% to 53% greater than those on low planes of nutrition (Labussiere et al., 2011). Emptying the rumen decreases energy expenditure by half, supporting the idea of energy expenditure being more dependent on substrate flow and metabolism than organ mass. The decrease in heat production was accompanied by an almost immediate change in fuel utilization increasing fat use dramatically; the animals were able to change its metabolism in matter of minutes going from postprandial to starvation (Torrent and Johnson, 1994). Kim et al., 2013 reported no significant differences in RQ and fasting HP in Holstein steers between the time segment of 9 to 16 h and 17 to 24 h after rumen washing. However, Hu (1994) reported that fasting heat production (FHP) (kJ / kg W0.75 /day) in growing yak remained fairly constant compared to that in the Qinghai yellow cattle.
From the present study it can be concluded that Net energy and ME requirement for maintenance (KJ/Kg W 0.75 of live weight) was lower in buffalo than cross bred cattle as they were producing low fasting heat as compared to cross bred cattle. Feeding rations with different roughage to concentrate ratio at maintenance level prior to fasting had no effect on fasting heat production.
The authors are thankful to the Director, ICAR- Indian Veterinary Research Institute, India for the facilities provided. The work was carried out using the institute fund provided for the project approved by The Director and the Joint Director (Research), ICAR-Indian Veterinary Research Institute.