Feed intake, digestibility, plane of nutrition and live
weight gain by crossbred growing bulls fed on
grainless diets containing different
nitrogen sources
S.S. Giri
*, A. Sahoo, N.N. Pathak
Animal Nutrition Division, Indian Veterinary Research Institute, Izatnagar 243122, Uttar Pradesh, India
Received 20 April 1999; received in revised form 27 October 1999; accepted 23 November 1999
Abstract
Twenty ®ve growing crossbred bulls (Bos indicusBos taurus) were used in a randomised block design experiment for 196 days to determine the effect of grainless concentrate containing different supplemental nitrogen sources along with wheat straw based diet on feed intake, nutrient digestibility, plane of nutrition and daily live weight gain. The animals in control group received barley 30% in the concentrate mixture (Cm1) as a source of grain, where as other concentrate mixtures contained only wheat bran (Cm2) or wheat bran supplemented with 2.5% urea (Cm3), 21.5% groundnut oil cake (Cm4) or 27% mustard oil cake (Cm5) as source of supplemental nitrogen. Fortnightly live weight gain was recorded and a metabolism trial of 6 days duration was conducted after 120 days of feeding trial in order to assess nutrient utilisation and retention as well as plane of nutrition.
The mean dry matter (DM) intake and digestibility of the nutrients except crude protein (CP) were similar in all the groups. CP digestibility was signi®cantly higher (P<0.05) in urea fed animals. A positive nitrogen balance was recorded in all the groups.
Though gross energy (GE) and digestible energy (DE) intake were not affected, the urinary loss of energy (UE) was signi®cantly lower (P<0.05) in animals fed Cm2. A positive calcium and phosphorus balance was observed in all the treatments though phosphorus balance in Cm2fed animals was signi®cantly higher (P<0.05).
Average daily live weight gains were 443, 344, 370, 435 and 423 g in Cm1, Cm2, Cm3, Cm4and Cm5fed animals, respectively. A marginal less daily live weight gain was recorded in Cm2fed animals and the results were non-signi®cant among the treatments. Active growth could be obtained
83 (2000) 195±203
*Corresponding author. Present address: Fish & Shell®sh Nutrition Division, Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar 751002, Orissa, India. Tel.: 91-674-465421; fax: 91-674-465407.
in animals fed grainless concentrates having wheat bran as its main component at an amount of 1% of the live weight daily without showing signi®cant in¯uence on nutritional status and growth of growing bulls.#2000 Elsevier Science B.V. All rights reserved.
Keywords:Crossbred bulls; Grainless diets; Nitrogen source; Digestibility; Performance; Wheat bran; Urea
1. Introduction
Agricultural crop residue such as wheat straw (Triticum vulgare) form the main source of cattle diet in Asia and has been studied extensively (Jayasuria, 1987). However, desired animal performance is very dif®cult to achieve when this forage is consumed alone. Due to continuous shrinkage of grazing ®eld, day by day intensive feeding is increasing. The farmers adapting stall feeding often face de®cit supply of good quality feeds and cereal grains. Under a situation of inadequate grain availability for livestock feeding, there has to resort a feeding system based on cereal by-products and ®brous crop residues. Wheat bran is a major milling by-product available in India and may act as a suitable cereal replacer in animal feeding. Other important aspect of feed component like protein, also needs serious consideration due to high cost of conventional oil cakes. Alternate low priced nitrogen sources may be incorporated in the grainless diets to minimise the cost of feeding. Keeping these facts in view, efforts were made to study the effect of different sources of nitrogen in grainless concentrate mixtures on nutrient utilisation and growth performance of growing crossbred bulls.
2. Materials and methods
2.1. Animals and feeding
Twenty ®ve growing crossbred bulls (Bos indicusBos taurus) of 18 months of age were distributed in the randomised block design in to ®ve equal groups with average initial body weight of 305.2, 310.4, 308.2, 310.4, 308.6 kg and fed on Cm1, Cm2, Cm3, Cm4 and Cm5, respectively, to determine the effect of receiving grainless concentrates containing different sources of nitrogen on performance and nutrient utilisation by the bulls. During experiment the animals were kept in well-ventilated sheds of Nutrition Division, Indian Veterinary Research Institute, U.P., with individual feeding arrange-ments. Clean drinking water was provided to all the animals twice daily at about 10:30 a.m. and 3:00 p.m. The experimental feeding was continued for a period of 196 days. All the animals were individually provided with weighed amount of wheat straw for ad libitum feeding and daily intake of wheat straw by each animal was determined by weighing the left over residue in the morning before offering the concentrates. The animals were fed concentrate mixture at 1% of the body weight on DM basis throughout the experimental period to meet the requirement (National Research Council, 1989) on respective diets. Wheat straw was offered to the animals only after complete consumption of the concentrate mixtures.
2.2. Preparation of concentrate mixtures
Five concentrate mixtures namely Cm1(control), Cm2, Cm3, Cm4and Cm5(Table 1) were prepared as iso-nitrogenous except Cm2, which contained 26±29% less protein. The standard concentrate mixture for control group contained barley as source of grain, and mineral mixture, which were not incorporated in Cm2, Cm3, Cm4 and Cm5. Calcium carbonate (chalk) was added in place of mineral mixture in the test diets, because wheat bran is de®cient in calcium and rich in phosphorus and micro minerals.
1 kg of green fodder was provided to each animal daily as the source of carotene. The left over residue of each animal was weighed after 24 h consumption to arrive at daily total feed intake. Fortnightly the animals were weighed in the morning before offering them feed and water to record the change in live weight gain and to calculate the requirement of concentrate mixtures. After 4 months of experimental feeding, a 6-day metabolism trial was conducted keeping the animals individually in the metabolic cages. Recording of feed and residue was carried out in all the animals after acclimatising them in metabolism cages for 3 days to attain uniform intake and output. Faeces were collected quantitatively from the collecting platform by hand picking, immediately after the defecation, while urine was collected continuously into the graduated plastic bottles from the collecting tray ®xed below the metabolic cages. The process of collection was continued round the clock during the entire period of metabolism trial.
Table 1
Ingredient (% on as such basis) and chemical composition (% on DM basis) of concentrated mixtures
Item Cm1 Cm2 Cm3 Cm4 Cm5
Ingredient
Barley 40 ± ± ± ±
Wheat bran 30 99 96.5 77.5 72
Mustard oil cake ± ± ± ± 27
Groundnut oil cake 28 ± ± 21.5 ±
Urea ± ± 2.5 ± ±
Common salt 0.5 0.5 0.5 0.5 0.5
Mineral mixture 1.5 ± ± ± ±
Calcium carbonate (chalk) ± 0.5 0.5 0.5 0.5
Chemical compositiona
OM 93.410.02 94.560.02 94.750.01 93.980.02 92.470.01 CP 19.720.02 14.530.01 20.500.01 19.620.02 20.380.01 EE 2.700.01 3.720.02 3.560.01 2.700.02 2.710.02 Total carbohydrates 70.990.02 76.310.02 70.690.01 71.660.02 69.380.02 NDF 38.190.03 40.240.02 40.900.01 42.410.02 46.230.02 ADF 10.700.02 9.490.02 9.410.02 10.730.03 14.000.03 Hemi cellulose 24.490.03 30.750.02 31.490.02 31.680.02 32.230.02 Ash 6.590.02 5.440.02 5.250.01 6.020.02 7.530.01 Calcium 0.830.02 0.530.01 0.510.01 0.540.02 0.580.02 Phosphorus 0.980.01 1.210.01 1.130.01 1.060.02 1.180.01 GE (kcal/g) 4.240.03 4.350.03 4.420.02 4.440.03 4.350.01
2.3. Analysis
The chemical composition of biological samples (feeds, faeces and urine) was determined by the method described by Association of Of®cial Analytical Chemist (1980). The ®bre fractions such as neutral detergent ®bre (NDF) and acid detergent ®bre (ADF) were analysed as per Robertson and Vansoest (1981). Total carbohydrate content of feed and faeces was determined by subtracting crude protein (CP) and ether extract (EE) from organic matter (OM). Gross energy (GE) of the samples was estimated by Gallenkamp Ballistic bomb calorimeter (CBB-330). Digestible energy (DE) was calculated by subtracting faecal energy (FE) loss from GE intake. Metabolisable energy (ME) loss was obtained by subtracting urinary energy (UE) and methane energy from DE. To arrive at the methane energy loss the total amount of methane produced was multiplied by its calori®c value (13.34 kcal/g). The methane production was calculated as per the equation suggested by Bratzler and Forbes (1940) for cattle,E4.012x17.68 (where, E is methane production in g and, x is hundreds of grams of fermented carbohydrates).
Calcium was estimated as per the method of Talpatra et al. (1940) where as phosphorus was determined by the method described by Association of Of®cial Analytical Chemist (1975).
The data were subject to test of signi®cance between diets using one way analysis of variance (Snedecor and Cochran, 1967).
3. Results and discussion
3.1. Dietary chemical composition
The chemical composition, ®bre fractions, calcium, phosphorus and GE content of the concentrate mixtures are given in Table1. The CP content in the Cm2was about 26±29% less than that of other concentrate mixtures because of the non-supplementation of nitrogenous feed ingredient in the mixture. It was formulated to contain lower nitrogen than the control concentrate mixture, which was necessary to observe the effect of supplemental nitrogen sources on the performance of bulls. Wheat bran contains more ®bre in comparison to barley (National Research Council, 1989). So, replacement of grain (barley) by wheat bran might have increased the NDF value in the test concentrates. The ®bre fractions were highest in Cm5 which might be due to higher ®bre content of mustard cake, in agreement to Ranjhan (1993). As bran is rich in phosphorus (National Research Council, 1989), variation in the content of the mineral in the concentrate mixtures was observed.
3.2. Body weight change
The initial average body weight of Cm1, Cm2, Cm3, Cm4and Cm5fed animals were 305.2, 310.4, 308.2, 310.4 and 308.6 kg which, respectively, became 392.0, 377.8, 381.8, 395.6 and 391.6 kg at the end of the feeding trial. The total body weight gain in different
groups were 86.8, 67.4, 73.6, 85.2 and 83.0 kg during entire experiment period with average daily gain of 443, 344, 370, 435 and 423 g, respectively. A marginal less weight gain was recorded in Cm2fed group because of long term feeding with low nitrogen-based diet. It indicated that replacement of grain by wheat bran with incorporation of nitrogenous feed ingredients in the diets of growing bulls did not affect daily live weight gain. The observed daily mean body weight gains were quite satisfactory for the bulls at this age.
3.3. Nutrient digestibility and plane of nutrition
There was no change in daily dry matter intake (DMI) among the treatment groups due to feeding of grainless diets. Earlier work of Mondal et al. (1996) also could not observe any signi®cant difference in DMI of growing cattle fed on grain, low grain and grainless diets. In the present study it was observed that sources of nitrogen did not in¯uence the DMI per unit body weight and was in agreement to the earlier ®ndings in the same line of work (Steen, 1989). The inclusion of 27% deoiled mustard cake (MOC) in Cm5did not reduce the palatability of the diet, as the same was also observed earlier by inclusion of 25% mustard cake (Sharma et al., 1977) or 33% rape seed cake (Lardy and Kerley, 1994) in the diets of cattle.
Intake and digestibility of DM and OM (Table 2) did not differ among the groups. The ®nding contradicts the observation of Malik et al. (1989) that replacement of 60% of maize grain by deoiled rice bran depressed the digestibility of all the nutrients in the diet of buffalo calves. The declined digestibility could not be observed in the present study which might be due to the presence of less total ash, particularly acid insoluble ash in wheat bran (Banerjee, 1986) compared to that of rice bran. Ministry of Agriculture, Fisheries and Food (1975) also suggested that the relative nutritive value of rice bran when fed to ruminants, must be considered inferior because of the presence of higher acid insoluble ash (silica) compared to other cereal by-products.
Table 2
Nutrient digestibility and plane of nutrition in growing bulls on different dietary treatmentsa
Digestibility (% ) Cm1 Cm2 Cm3 Cm4 Cm5
Dry matter 60.571.57 57.701.35 59.571.56 57.980.94 58.061.22 Organic matter 65.331.58 61.871.17 63.091.52 62.300.85 61.841.14 Crude protein* 67.001.44 b 60.571.61 c 71.900.91 a 63.901.01 bc 63.391.40 c Ether extract 63.711.88 63.851.47 63.151.59 61.632.89 60.121.33 Total carbohydrate 64.951.64 61.791.12 61.891.62 62.070.95 61.711.32 Neutral detergent ®bre 50.422.82 47.381.31 50.171.22 48.971.16 51.121.48 Acid detergent ®bre 40.763.61 38.111.71 39.920.76 37.882.03 42.291.53 Hemicellulose 59.611.24 55.571.05 58.901.52 58.840.96 59.501.52
TDN intake
kg per day 4.250.23 3.940.27 4.010.20 4.280.24 4.270.26 g kg Wÿ0.75 50.951.60 47.791.12 48.081.03 49.421.60 49.880.65
The CP digestibility in Cm3was higher (P<0.05) compared to other diets because of the presence of urea in the concentrate mixture, a source of highly rumen degradable nitrogen. The lower digestibility of CP in Cm2and Cm5might be attributed to lower CP content in the former diet, agreeing to the earlier studies (Horn et al., 1979; Baruah et al., 1983) and a probable suppressive effect of MOC on proteolytic activities of ruminal microbes, in the later, supporting the observations of Sil et al. (1994) and Fisher and Walsh (1976), in cattle. The variation in intake of EE was due to compositional variation of the diets and no signi®cant difference could be marked in the digestibility of the nutrient among the groups. The difference in intake and digestibility of NDF, ADF, hemicellulose and total carbohydrates could not be observed among the treatments. This clearly indicated that replacement of barley in the diets of growing bulls by wheat bran would not in¯uence the digestibility of these dietary components.
3.4. Nutrient retention
The values of mean intake, excretion through faeces and urine and retention of nutrients are presented in Table 3. The nitrogen intake was lowest (P<0.05) in Cm2fed bulls, so also the excretion through faeces and urine. Hence, a positive nitrogen balance was observed. The ef®ciency of nitrogen retention is generally more with a reduced level
Table 3
Mean daily retention of nitrogen, calcium and phosphorus (g per day)a
Attributes Cm1 Cm2 Cm3 Cm4 Cm5
Nitrogen
Intake** 133.200.23 a 98.000.21 b 131.600.21 a 135.400.18 a 140.800.22 a Faecal excretion** 44.154.25 ab 38.762.97 ab 36.921.90 b 48.952.91 a 51.845.17 b Urinary exertion** 70.424.59 a 41.602.07 b 76.684.76 a 70.895.78 a 70.567.03 a Balance 19.202.54 17.602.06 17.800.73 15.602.27 18.002.19 g kg Wÿ0.75per day 0.230.03 0.210.02 0.210.01 0.180.03 0.220.04 % of N-intake 14.512.01 17.931.79 13.640.81 11.852.21 13.422.48 % of N-absorbed* 21.482.81 b 29.352.29 a 18.971.10 b 18.603.49 b 20.923.44 b
Calcium
Intake** 42.452.66 a 30.001.65 b 29.541.41 b 33.201.55 b 35.182.80 b Faecal excretion* 32.273.02 a 22.672.48 b 21.491.69 b 25.151.76 b 26.322.37 ab Urinary excretion** 3.080.59 a 1.140.24 b 1.190.25 b 1.100.15 b 1.270.19 b Balance 7.111.08 6.211.07 6.881.08 6.750.73 7.580.95 % of Ca-intake 16.872.47 20.704.99 23.273.54 20.642.68 21.553.53 % of Ca-absorbed* 69.452.96 b 84.632.02 a 84.952.20 a 83.903.55 a 85.463.50 a
Phosphorus
Intake 38.432.31 44.632.85 41.802.14 42.721.97 47.113.47 Faecal excretion 20.872.10 22.161.50 23.053.34 27.002.69 32.433.43 Urinary excretion** 3.620.57 a 3.610.62 a 3.330.35 a 2.360.38 ab 1.590.20 b Balance* 13.930.75 b 18.871.92 a 15.421.57 ab 13.361.29 b 13.091.09 b % of P-intake 33.613.73 42.112.56 37.743.16 31.553.24 28.183.18 % of P-absorbed* 79.782.43 76.272.41 80.452.86 84.181.64 89.161.15
aMean values bearing different letters in a row differ signi®cantly. *P<0.05, **P<0.01.
of CP in the diet of ruminants (Dass and Arora, 1989; Giri and Dass, 1993). In Cm3fed animals faecal nitrogen loss was lowest and urinary nitrogen output was highest in comparison to that of other groups. It was supposed that urea in the diet hydrolysed quickly in the rumen and released ammonia. Part of the released ammonia was trapped by the microbes for synthesis of their own body protein and rests were absorbed through the rumen epithelium, converted into urea in the liver and excreted through urine. Hence, an increased urinary output of nitrogen was observed. However, the positive nitrogen balance was observed for all the animals of different dietary treatments.
The calcium content in Cm1was higher, so increased intake of the mineral was obvious in animals fed on control diet. The total excretion of calcium through faeces and urine was also higher in those animals. A positive calcium balance was observed in all the groups. Trends in phosphorus intake and excretion were different from that of calcium. The balance of phosphorus in Cm2was higher (P<0.05) than in the other groups. Moran (1983) also observed the same trend of calcium and phosphorus balance in Ongole steers and Swamp buffaloes when rice bran was supplemented to elephant grass-based roughage diet.
Table 4
Energy distribution in bulls during metabolism trial (per day)a
Attributes Cm1 Cm2 Cm3 Cm4 Cm5
Gross energy intake
Mcal 27.992.35 26.701.49 27.181.31 30.071.05 29.872.42 kcal kg Wÿ0.75 3368.60 3258.41 3265.71 3488.00 3487.20
Faecal energy
Mcal 11.360.98 10.880.80 12.781.79 12.330.50 12.461.17 kcal kg Wÿ0.75 1337.40 1324.60 1294.80 1434.00 1456.50 % of GE 38.821.10 40.561.11 39.581.02 40.980.41 41.560.60
Digestible energy intake
Mcal 16.630.89 15.870.76 16.400.72 17.740.58 17.401.26 kcal kg Wÿ0.75 1994.80 1936.80 1973.90 2054.50 2035.03 % of GE 59.411.07 59.441.11 60.421.01 59.020.41 58.440.60
Urinary energy
Mcal** 57627 a 34810 b 57931 a 68549 a 61892 a kcal kg Wÿ0.75** 6.940.40 a 4.270.21 b 6.970.36 a 7.940.57 a 7.130.77 a % of GE** 2.060.13 a 1.320.07 b 2.140.10 a 2.290.19 a 1.980.21 a
Methane energy
Mcal 2.160.10 2.040.13 1.950.09 2.140.11 2.130.12 kcal kg Wÿ0.75 25.860.79 24.740.53 23.410.40 26.591.62 24.890.15 % of GE 7.720.21 7.610.12 7.160.18 7.120.16 7.180.20
Metabolisable energy intake
Mcal 13.890.79 13.480.65 13.870.63 14.900.49 14.651.07 kcal kg Wÿ0.75 1674.40 1646.50 1663.80 1734.30 1714.30 ME:GE ratio 0.500.010 0.520.019 0.510.009 0.500.005 0.490.005 ME:DE ratio 0.840.002 0.850.004 0.850.002 0.840.004 0.840.004
The GE intake and FE excretion (Table 4) was not signi®cantly different among the treatments. It indicated that grain replaced by wheat bran did not in¯uence FE excretion. So, no signi®cant difference could be observed in DE intake between the treatments. The signi®cantly lower (P<0.05) urinary excretion of energy was observed in Cm2fed bulls because of less excretion of nitrogen in urine. Similar low urinary loss of energy was also reported by Raven (1972) and Moran (1983) in cattle fed on forage-based diets supplemented with rice bran. Energy lost as methane was calculated to about 7% of GE intake in all the animals. In this regard Moran (1983) indicated that supplementation of bran to the roughage diet did not in¯uence the methane energy loss in cattle. The mean intake of ME in all the groups was alike. ME:GE and ME:DE ratios were also not signi®cantly different among the dietary treatments.
4. Conclusion
The value of wheat bran with supplementation of urea or oil cakes when provided at 1% the of body weight for wheat straw fed, growing bulls, as assessed by daily live weight gain, was at par with that of grain based concentrate fed at the same percent of body weight. The value of wheat bran supplemented at 1% of live weight either independently or mixed with 2.5% urea or 21.5% groundnut oil cake or 27% mustard oil cake did not in¯uence much in comparison to barley-based concentrate mixture with respect to nutrients digestibility, energy, calcium and phosphorus balances by crossbred bulls, fed on wheat straw as the basal roughage.
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