Livestock contribute 55.4% to agriculture and 11.9% to national GDP. Main products of livestock are milk and meat. Meat industries are increasing day by day. In 2013 the meat production has increased from 3232000 tons to 3379000 tons (Anonymous et al. 2013). We can achieve the growing meat demand inside the country and can earn a bit foreign exchange by exporting meat. Fortunately Pakistan is the home tract of finest natural breeds of livestock. Nili Ravi buffalo breed is one of them. Dairy animal can be used for meat production especially male calves and dairy bulls that are no more needed for breeding can be utilize for beef purpose. Fattening is the one of major field in the livestock sector. In fattening economics should be considered to make it profitable, for this purpose the use of low price feed with high nutritive value is more important. In Pakistan the animal feeding consists of crop residue, mainly wheat straw and stovers etc. These crop residues are poor in palatability, digestibility and nutrients (protein, minerals and vitamins).Urea increases the nitrogen availability which in turn improves the protein content (Khan et al. 1999; Rath et al. 2001). It is the need of hour to explore our existing livestock resources to fulfill the animal protein requirements of growing human population. This target can be achieved by optimizing the forage and fodder production. In Pakistan the main focus is cultivation of cash crops instead of fodder crops, less fodder crop cultivation and low quality forages are the main factors that badly affect the animal production. In future due to increasing human population animals will have to rely on forages because there will be direct competition between humans and animals for grains. To avoid this problem we must use the cheap and economical products in ration to fulfill the nutritional requirement of animals. In the tropical areas low quality forages and high priced protein sources such as soybean and other oil cakes are the main constraints in the livestock feeding.proteína de los pastos tropicales y el alto costo de fuentes alternas de proteína como es latorta de soya. This protein deficiency can be fulfilled by the addition of non-protein nitrogen source (urea) which hydrolyzed into ammonia in the rumen, which in turn utilized by the ruminal microbes to synthesize protein.
The most common non-protein nitrogen (NPN) source used in ruminant feeding is urea, due to its low cost; thus, when prices of protein feeds escalate (i.e., soybean meal), it is economical to use urea as a nitrogen supplement in ruminant diets. Using the protein equivalent of 287%, incorporation of one unit of urea in a diet can replace five units of soybean meal. However, the final decision is not just a matter of a mathematical substitution. The amount of NPN that can be used is limited due to the rapid hydrolysis of this N source, which causes accumulation and escape of ammonia from the rumen (Satter and Roffler, 1975).La cantidad de NNP que puede ser suministrada es limitada.The use of NPN (Urea) in ration is limited because El producto más usado es lait is readily converted into NH33más rápido de lo que puede ser convertido en proteína. This faster release causes over production of ammonia which is absorbed by rumen wall and cause toxicity.microbiana, el exceso de NH(Velez et al. 2006). To avoid this faster release of ammonia and optimizing the nitrogen availability,Teniendo en cuenta las limitantes para el uso de urea en la alimentación, se handesarrollado varios métodos de utilización de la misma: Bloques multinutricionales, urea various methods for the use of NPN products as in form of multi nutritional blocks, urea con melaza más limitadores de consumo como es el ácido fosfórico, y el uso de unmolasses block and in the form of compuesto con liberación lenta de la urea como Optigenslow release urea compound as Optigen. ??®.Debido a que OptigenAs Optigenes una fuente concentrada, los productores ganan espacio en lasis a concentrated NPN source, producers are adding optigen by replacing other protein sources, so other ingredients can be addedingredientes, como forraje o subproductos, los cuales pueden mejorar la salud del rumen,, such as fodder or byproducts, which help in reducing the ration cost in addition to the improvement of rumen health and el bienestar animal y reducir los costos de las dietas.animal welfare. Dietas balanceadas con Optigen Balanced ration containing Optigen ??®promueven un mejor crecimiento de las bacterias fibrolíticas las cuales requiere NNPenhance the growth of fibrolytic bacteria which utilizes non-protein nitrogen (NPN)para su desarrollo, mayor producción de proteína microbiana y una mejor gestión for development, optimizing microbial protein production and better ambiental del nitrógeno (Alltech Inc. 2004).nitrogen managing environment (Alltech Inc. 2004). Urea is the cheap and most common non protein nitrogen source used in ruminant’s feed. Thus, when the prices of other protein source (i.e., canola meal, soybean meal etc.) increase the inclusion of urea as a replacement is feasible because it provides nitrogen to the ruminal microbes to synthesize protein. Domestic animals that were offered NPN compounds show inconstant results. (Foreroet al. 1980; Owenset al. 1980; Loestet al. 2001), this might be due to faster release of ammonia exceeding the capacity of ruminal microbes to synthesize the protein. (Galoet al. 2003). Though some slow-release NPN products have efficiently alleviated rapid ammonia production in the rumen (Huntingtonet al. 2006) and improve the ration efficacy in dairy cows, when soybean meal was replaced by slow release NPN compound. (Golombeskiet al.2006). Keeping in view above facts, study was designed to evaluate the efficacy of urea and optigen (NPN slow release) on the performance of Nili Ravi buffalo calves.
Material & methods:
Experimental Site and Design
Total fifteen male buffalo calves were selected and raised at livestock experimental station of Buffalo Research Institute, Pattoki. Fifteen male buffalo calves of proximately same age and body weight (200±25 kg) was divided into three groups, 5 animals in each group. Control group (A), urea supplement group (B) and Optigen supplemental group (C). Animals were given 10 days adaptation period at the start of experiment. At the start of experiment animals were weighed and then weighed fortnightly during 90 days trial. Animals were placed in separate pens. Fresh water was available in the water tubs round the clock during experimental period. The animals were fed at ad libitum. Feed offered and refusal was recorded daily and was composited by animals for the following analysis.
Feed intake was measured every day and Body weight of calves of each group was measured at the start of experiment and then on the fortnightly. Average Daily weight gain (ADG) was also measured on the fortnightly basis by dividing the weight gain by number of days. Feed intake and weight gain data then used for the calculation of feed efficiency. Blood samples were collected on fortnightly basis 2 hours after feeding. Blood Urea Nitrogen (BUN) and Blood Glucose (BG) was analyzed from blood samples at University diagnostic laboratory UVAS Lahore.
The experiment was arranged under completely randomized design (CRD) and the data obtained was the subjected to Analysis of Variance Technology. The difference among means was tested through Least Significant Difference (LSD) Test (Steel et al. 1997).
Results and discussion
The effects of experimental diets on daily feed intake of fattening male buffalo calves are shown in Table 3. Results showed that difference between diets on daily feed intake was significant (p<0.05). Calves fed 1% urea showed increase feed intake than others. These findings are in line with previous studies who explained that increase in feed intake was due to urea treated feed (Trishna et al. 2012, Barque et al. 2008, Nisa et al. 2008, Parsad et al.1998). However these findings do not agree with Bourg et al. (2012) and Koster et al. (2002) who reported that feed intake was unaffected when urea and optigen added in feed.
The effect of increased urea proportion in dry matter intake has been variable. Some workers observed a depression in intake (Foreroet al., 1980 and Kosteret al., 1997), whereas others have reported an increase or no effect (Kosteret al., 2002). Higher levels of urea tended to affect the palatability of ration as reported by Erfle et al. (1978) in lactating cows. Similarly Pond and Yen (1985) observed lowered feed intake in ewes given basal diet having 1 % urea than those fed basal diet alone. Casper and Schingoethe (1986) also noted a depression of dry matter intake in cows fed a concentrate mixture containing urea. In lactating cows, decreased intake of silage and total dry matter due to feeding of urea were reported by Huber et al. (1980). In contrast, daily feed intake of bulls given wheat straw and a concentrate mixture with urea at 0, 0.75, 1.50 or 2.25 percent levels was not adversely affected (Colpan, 1983). Ho Quanget al., (1999) also reported that increasing of urea in the feed decreases the intake.
Diets effects on daily weight gain on fattening male calves were significant (p<0.05). According to results, daily weight gain were greater for animals fed diet containing 1% urea compared to other diets. Our findings are in agreement with previous studies (Tedeschi et al.2002, Trishna et al. 2012, Sarwar et al. 2006, Chemjong 1991) who explained that increase in average daily weight gain was due to urea treated feed. However study of Muro et al. (2011) disagreed with the results of present study, he reported that slow release NPN (Optigen) have good effect on average daily gain in comparison to urea in Holstein heifers (Table 3).The addition of urea at 0.5 percent level to a low protein basal diet (14 percent nitrogen equivalent) had not been shown to exert any significant influence on weight gain of bulls (Rakhimovet al., 1984). The use of urea at such a low level as employed in the present study did not indicate any adverse effect on the weight gain of the buffalo calves. This tended to suggest that the type of concentrate, i.e. low or high protein content did not matter much with respect to growth promotion when urea was fed at lower levels. Similar results were obtained by Reddy and Mudgal (1985) by incorporating urea in a concentrate mixture to provide 50 percent digestible crude protein. The present results based on the use of urea below 2 % level in male buffalo calves are in agreement with their findings on the weight gain of buffalo heifer calves. This presumably indicated that weight gain in male and female buffalo calves was of the same magnitude with urea fed at levels given above. The present results are also substantiated by those of Sharma et al., (1983) who observed no significant difference in weight gains of calves that were fed urea to contribute 60 percent nitrogen to the rations. Similarly non-significant differences were observed in the weight gain of young male cattle given 2.0 % urea in the ration (Holub and Marounek, 1985). It may be stated that feeding urea up to 2.0 % level could be economical in raising buffalo calves under existing farm conditions. On the other hand, Langaret al.. (I984) showed that in buffalo heifer calves, an addition of 2.3 percent urea in a concentrate mixture containing maize, groundnut cake and wheat bran did not exert any adverse effect on the weight gains. This probably indicated that the safe limit on the use of urea is between 2.0 and 2.5 percent level of the diet. Significant improvements in weight gain were observed due to feeding of ammoniated wheat straw under stall-fed condition (Misraet al., 2006). Feed conversion ratio of animals did not significantly affected by experimental diets.
The average blood glucose values showed non-significant (p>0.05) difference between all the groups. The average blood glucose level of all the Nili-Ravi buffalo male calves in each group A, B and C was 50.24 mg/dl, 50.14 mg/dl and 49.36 mg/dl respectively. Similar findings were reported by Colovos et al. (1967). The results of Chaudhary and Srivastava (1996), disagrees with the results of present study, who explained that blood glucose level was increased in buffaloes using NPN source.
The results of blood urea nitrogen (BUN) in all groups (A, B and C) were non-significant (p>0.05). The average blood urea nitrogen (BUN) level of all the Nili-Ravi buffalo male calves in each group A, B and C was 14.45 mg/dl, 14.99 mg/dl and 14.78 mg/dl respectively. The findings are in line with Nadeem et al. (2014) who explained that the blood urea nitrogen level was unaffected in Nili-Ravi buffaloes. Currier et al., 2004 conducted a study in Angus and Hereford Cows and observed the effect of urea supplementation on BUN level, contrary to the results of the present study.
The analysis of the results suggests that including 1% urea in the feed of calves can improve feed intake, feed conversion ratio and daily weight gain more efficiently than other NPN sources (optigen). Moreover, use of urea is more economical for fattening of Nili Ravi buffalo calves. Further research should be done to evaluate the ruminal pattern of bacteria in order to better describe the biological effects of urea and slow-release products in the rumen.
I am thankful to Dr. Sajid Umar, Dr. Abdur Rahman, Dr. Afzal Rashid, Dr. Zeeshan Iqbal, Dr. Muhammad Ali and Mr. Hanif for their help, support and cooperation throughout the trial.
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Table:1 Feeding Groups and Treatments:
Table:2 Ingredients and chemical composition of feed
Table: 3 Mean feed intake (Kg) and weight gain of buffalo Calves of Groups A= Control, Groups B= Urea and Group C= Optigen. The data were presented as Mean ± SE.
Table: 4 Mean blood glucose level (mg/dl) and blood urea nitrogen (mg/dl) of buffalo Calves of Groups A= Control, Groups B= Urea and Group C= Optigen. The data were presented as Mean ± SE.