Phone : 0092 300 7786573

Advances in Animal and Veterinary Sciences

Download PDF Download ePUB
AAVS_ MH20160829160859-R1_Zulfiqar Ahmed et al



Research Article


Effect of Slow Release Urea Supplementation (Optigen®) on the Production Performance of Kaghani sheep


Zulfiqar Ahmed*, Shahzad Akbar Khan, Mohsin Nawaz, Asim Shamim, Muhmmad Waqas, Ibrar Mohi-uddin, Imran Ahmed, Zulfiqar Hussan Kuthu, Faisal Rasool

Faculty of Veterinary and Animal Sciences, The University of Poonch, Rawalakot-Azad Jammu and Kashmir, Pakistan.


Abstract | The study was conducted to evaluate the effect of slow release urea supplementation (Optigen®) on the growth performance of grazing Kaghani sheep with special reference to weight gain, fleece weight and wool quality. Thirty healthy post-weaned male lambs of Kaghani sheep were selected and divided into two groups viz Group-A (treated group) and Group-B (control group) containing fifteen animals each. Sheep in both groups were kept on grazing and maize silage feeding ad libitum; however sheep in group A were additionally supplemented with Optigen® at the dose rate of 10 grams/animal twice a day for 60 days. The animals were weighed individually at the start of experiment and weekly thereafter. Sheep were shorn at the end of experiment and fleece weight was recorded. The fiber types were determined by Benzol method before and after the experiment. Average body weight and fleece weight of animals treated with Optigen® was significantly (P<0.05) higher as compared to control group. True, kemp and modulated fiber’s quality was significantly (P<0.05) improved except heterotypical fiber with the Optigen® supplementation. It was concluded that slow release urea supplementation (Optigen®) with maize silage feeding was effective in increasing body weight, fleece weight and wool quality in growing lambs.


Keywords | Fleece weight, Kaghani sheep, Optigen®, Weight gain, Wool quality


Editor | Kuldeep Dhama, Indian Veterinary Research Institute, Uttar Pradesh, India.

Received | August 30, 2016; Accepted | March 21, 2017; Published | April 04, 2017

*Correspondence | Zulfiqar Ahmed, Faculty of Veterinary and Animal Sciences, The University of Poonch, Rawalakot-Azad Jammu and Kashmir, Pakistan; Email:

Citation | Ahmed Z, Khan SA, Nawaz M, Shamim A, Waqas M, Mohi-uddin I, Ahmed I, Kuthu ZH, Rasool F (2017). Effect of slow release urea supplementation (optigen®) on the production performance of Kaghani Sheep. Adv. Anim. Vet. Sci. 5(4): 155-159.


ISSN (Online) | 2307-8316; ISSN (Print) | 2309-3331

Copyright © 2017 Zulfqar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.




Small ruminants’ rearing is an important agricultural subsector in developing countries where these animals are kept for mutton, wool and milk purposes (Devendra and Burns, 1970). Pakistan has well distinguished 28 breeds of sheep including Kaghani sheep (Ahmad et al., 2001). Kaghani sheep is a medium sized low producer breed and normally graze traditionally on naturally grown grasses (Rafiq et al., 2013; Nawaz et al., 1992). Small ruminants are valuable animal resource but paid no value in developing countries like Pakistan (Sarwar et al., 2010). These are reared solely on the grazing and are not fed with any supplementary ration (Liesegang et al., 2008). Such under nourished sheep marketed and slaughtered for mutton or wool purpose are mostly lean and emaciated. The body weight considered as great bearing due to the mutton producing capacity of sheep (Afzal and Naqvi, 2003-04).


Intensive production system was introduced in developing countries based on concentrate feed stuffs, smaller use of grazing and pastures, early weaning and introduction of exotic improved breed but failed due to high production costs (Morand-Fehr and Boyazoglu, 1999). The alternative is to improve the performance of sheep in existing grazing system (Dickhoefer et al., 2014). Dietary proteins are important in ruminant’s nutrition because they serve as a source of amino acids and nitrogen for the synthesis of microbial protein (Kaur and Arora, 1995; Nocek and Russell, 1988). The use of non-protein nitrogen (NPN) compounds can be used as alternative to grasses, fodder and concentrates of low nutritive value (Cherdthong and Wanapat, 2010; Burgstaller, 1983). Urea is a source of non-protein nitrogen (NPN) for growing lambs because of its low cost compared to other NPN sources and protein feeds (Colmenero and Broderick, 2006). Addition of slowly released ruminal urea compounds has a long history in ruminant feeding (Kertz, 2010). Slowly rumen released nitrogen compounds primarily stems from their potential to release slow ammonia post-feeding, thereby decreasing peak ammonia concentrations in the rumen (Pinos-Rodriguez et al., 2010). Slow released urea causes minimum utilization of urea by ruminal microflora and increased absorption from the rumen (Taylor-Edwards et al., 2009).


The total sheep population of Pakistan is 29.1 million (Anonymous, 2013-14). Keeping in view the importance of sheep and the need to meet their nutritional deficiencies, the present study was conducted to evaluate the effect of slow release urea compound (Optigen® Alltech Int.) on the growth performance of grazing Kaghani sheep.




Source Of Animals


The trial was conducted at Livestock Research Station, Jaba, District Mansehra, Khyber Pakhtunkhwa, Pakistan. Thirty post-weaned male lambs of Kaghani sheep breed with age group of < 1 year and weight ranging 13 to 25kg were incorporated in this study.


Grouping Of Animals


Thirty animals were equally divided into two groups (Treatment-A and Control-B) containing fifteen animals each. Both experimental groups were subjected to identical grazing and were offered maize silage feeding ad libitum (Saric et al., 2013).


Supplementation Trial


All animals were dewormed with Albendazole (Albavet®) at the dose rate of 7.5 mg/kg body weight one week prior to the start of trial. Treatment group was fed with urea Optigen® at the dose rate of 10 grams/Animal (as per labelled manufacturer dose) twice daily at 09:00 AM and 15:00 PM for a period of 60 days, whereas control group was kept on grazing and maize silage feeding ad libitum without any supplementation. Amount of feed offered was recorded daily. Animals were maintained at ambient temperature and natural day length with clean drinking water availability. Initial and weekly body weights of individual lambs were recorded with electronic weighing balance throughout the trial period.


Determination Of Fleece Weight And Fiber Type


At the end of the experiment, animals were shorn and fleece weight was measured with electronic weighing balance. Fiber types for wool quality were determined by Benzol method (Elphick, 1932). One hundred (100) fibers were picked with the help of forceps and dropped one by one into petri-dish containing Benzol solution for visibility test. Fibers visible through the entire length were considered as modulated and kemp fibers (kemp fibers were chalky white, coarse and opaque in appearance), partially visible as heterotypical and totally invisible as true wool fibers. Thus, 100 fibers from each sample were examined before and after the experiment and proportion of each fiber type was recorded in percentage.


Statistical Analysis


Data collected regarding the weight gain, wool production and wool quality were analyzed using analysis of variance technique (ANOVA), Completely Randomized Design (CRD), while Least Significance Difference (LSD) test was used to compare means. Data were analyzed using computer based software Statistix8.1®.



Weight Gain


The mean initial and final body weights of lambs did not differ significantly across the groups. However, the average body weight gain was significantly (P<0.05) higher in Optigen® group as compared to control group (Table 1). The results showed that significant (P<0.05) linear increase in body weight of Optigen® group was observed from day 0 to day 60. The change in the body weight of sheep in control group was non-significant throughout the period (Table 2).


Fleece weight: The fleece weight between the two groups was significant different. Treatment Group (Optigen®) yielded significantly higher (P<0.05) fleece weight as compared to the control group (Table 3).


Table 1: Comparison of body weight gain in Optigen® and control groups



Initial Weight (Kg)

Final Weight (Kg)

Mean of Initial and final Body Weights(Kg)

Average Weight Gain (Kg)


18.3 ±0.86


19.65 ± 0.38





20.41 ± 0.32



Different superscript letters along the columns indicate significant differences (P < 0.05)


Table 2: Effect of Optigen® on body weight in growing lamDifferent superscript letters along the columns indicate significant differences (P < 0.05)



Day 0

Day 15

Day 30

Day 45

Day 60


18.3 ± 0.85a

18.83 ± 0.83ab

19.56 ± 0.84ab

20.36 ± 0.85ab

21.21 ± 0.85b


19.9 ± 0.75

20.04 ± 0.73

20.3 ± 0.73

20.6 ± 0.72

21.04 ± 0.73


Table 3: Comparison of average fleece weight in the optigen® and control groups



Fleece weight after treatment (Kg)

Optigen (n = 15)

2.2 ± 0.04a

Control (n = 15)

1.94 ± 0.02b


Different superscript letters along the columns indicate significant differences (P<0.05)


Modulated fiber: No significant difference was observed in the modulated wool fiber in both Optigen® and control groups at the start of the experiment. However, significant decrease (P<0.05) in modulated wool fiber was observed at the end of the trial in the Optigen® group. But it remained same in case of control group (Table 4).


Table 4: Comparison of wool fibers in the Optigen® and control groups at the start and end of experiment


Fiber types



Start of experiment (%)

End of experiment (%)

Start of experiment (%)

End of experiment (%)

Modulated fiber

26.6 a

19.07 b

26.4 a

25.9 a

Heterotypical fiber





True wool fiber

21.5 a

30.9 a

21.9 a

22.8 b

Kemp fiber

1.4 a

0.5 a

1.6 a

1.8 b


Different superscript letters along the columns indicate significant differences (P < 0.05)


Heterotypical wool fiber: The data showed that at the end of experiment the percentage of heterotypical wool fiber was 49.4% for Optigen® and 49.3% for control group respectively. A non-significant difference was observed between the groups before and at the end of the trial (Table 4).


True wool fiber: The data showed that at the start of the experiment there was no difference in the true wool fiber in both Optigen® and control groups. The true wool fibers in Optigen® and Control group were 30.9 and 22.8 % respectively. A significant (P<0.05) difference between the Optigen® and control groups was recorded (Table 4).

Kemp wool fiber: The data showed a non-significant difference at the start of the experiment between the groups 1.4% for Optigen® and 1.6% for control group. However, at end of the trial significant decrease (P<0.05) in kemp wool fiber was observed in the Optigen® group (0.5%). But in case of control group it remained same (1.8%) during the treatment group (Table 4).


It is evident from the above results that the all types of fibers except heterotypical fiber, were significantly (P<0.05) affected by the Optigen® supplementation in the maize silage during feeding.


Studies upon the performance of lambs based on slow release urea supplementation shows variable effect on weight and feed intake. According to Harris and Mitchell, 1941a,b, Johnson et al. (1942) and Johnson et al. (1944), growing and fattening lambs could gain in body weight and store body nitrogen provided with rations containing 40-65 percent of the nitrogen in the form of urea. Hamilton et al. (1948) and Tillman and Swift 1953, observed balance studies in Illinois showed that nitrogen in the form of urea was as well utilized as equal nitrogen and considerable effect on weight gain in growing lambs. Hue et al. (2008) concluded that slow release urea product could be used as protein sources in diets straw based and replace a commercial concentrate without any effect on the live weight gain of the lambs. The findings of the present study are in line with Yirga et al. (2011) who concluded that lambs fed with slow release urea product based diet with minimum concentrate mix resulted in better biologic and economic performance. The findings are not in line with Lizarazo et al. (2104) who declared that slow-release urea (SRU) with a source of soluble carbohydrates on ruminal fermentation in lambs nourished with low quality forage hay has no effect on the rumen digestibility of dry matter (DM) and neutral detergent fiber (NDF) or the rate of microbial protein synthesis in growing lambs. The findings of the present study are different from that of Hernandez et al. (2011) who reported that the addition of the slow release urea had no effect on the productive parameters or indicators of rumen fermentation. Golombeski et al. (2006) and Highstreet et al. (2010) reported that slow release urea can negatively affect finishing rations when added with fibrolytic enzyme. Use of urea is also related with the advantage of hydrolysis to NH3-N in the rumen by microbial enzymes


In the current study, it has been observed that the supplementation of NPN in slow released form provided a significant effect over the wool characteristics. However, there are scanty reports available on feeding of urea as nitrogen source on wool production. Most of the studies reported no improvement on wool production in diets containing supplemental urea. According to Peirce (1951), the addition of 15g urea along with low protein ration containing a high proportion of fiber did not show any significant effect, however an increase of 32 per cent in total wool production was recorded with 15g urea along with low protein ration containing high proportion of a carbohydrate (potato starch). The findings of our study are not similar to Lofgreen et al. (1953) and Aitchison et al. (1988) who reported that urea supplementation provided with either molasses or in pellets with grain and other feeds to sheep, had no improvement in wool production. According to Black and Reis (1979), urea treatment of the straw has no significant improvement in wool growth rates. Another study conducted by Hynd et al. (1986) also suggests that 6 weeks may be required for wool growth to truly reflect dietary changes. However the findings of the present study are in some sort of similarity with findings of Coombe and Tribe (1962), Coombe and Preston (1969) and Knox and Steel (1999), who observed an improvement in the wool growth of sheep supplemented with urea and molasses fed diets containing low quality roughages.




It has been concluded from the above discussion that fibrous diet for ruminants can be manipulated by various ways and maize silage supplemented with Optigen® is healthy tool to improve weight gain and wool production in growing lambs. However, longitudinal study is required to evaluate growth performance, wool quality, feed intake, fermentation and digestibility of slow-release urea products with low grade forages during different seasons.




The authors are highly thankful to the Station Director, Livestock Research Station, Jaba, District Mansehra, Khyber Pakhtunkhwa, Pakistan for his sincere guidance and cooperation for conducting this valuable research work.




The authors declare that there is no conflict of interests regarding the publication of this article.




ZA designed and conducted the study; SAK helped in coordination and drafting of the manuscript; MN and IM contributed in the searching of research and review articles related to the study design; MW and ZHK contributed in the better explanation of the Slow release urea supplementation; and AS,I A and FR participated in the sequencing of this research article. All authors read and approved the final manuscript.




  • Afzal M, Naqvi AN (2003-04). Livestock resources of Pakistan: present status and future trends. Q. Sci. Vis. 9 (1-2, 3-4): 1-14.
  • Ahmad Z, Yaqoob M, Younas M (2001). The Lohi sheep: a meat breed of Pakistan review. Pak. J. Agric. Sci. 38(3-4): 69-72.
  • Anonymous (2013-14). Economic survey of Pakistan, finance division, economic advisors wing, ministry of finance, Government of Pakistan. Islamabad. pp. 37.
  • Aitchison EM, Rix GS, Rowe JB (1988). The effect of urea treatment of straw and lupin supplementation on intake, live weight changes and wool growth in sheep. Proc. Aust. Soc. Anim. Prod. 17: 134-137.
  • Black JL, Reis PJ (1979). Physiological and environmental limitations to wool growth, Unit 61 University of New England Publishing.
  • Burgstaller G (1983) Practical cattle feeding. 3rd Ed. Verlag eugen ulmer, stuttgart, Germany. 19-24.
  • Cherdthong A, Wanapat M (2010). Development of urea products as rumen slow-release feed for ruminant production: A Review. Aust. J. Basic Appl. Sci. 4(8): 2232-2241.
  • Colmenero JJ, Broderick GA (2006). Effect of amount and ruminal degradability of soybean meal protein on performance of lactating dairy cows. J. Dairy Sci. 89(5): 1635-43.
  • Coombe JB, Tribe DE (1962). Feeding of urea supplement to sheep and cattle: The result of penned feeding and grazing experiments. J. Agric. Sci. 59(1): 125-141.
  • Coombe JB, Preston GK (1969). The effect of urea on the utilization of ground, pelleted roughage by penned sheep: I. Food intake, live-weight change and wool growth. J. Agric. Sci. 72(2): 251-259.
  • Devendra C, Burns M (1970). Goat production in tropics. Tech. Commun. Commonwealth Bur. Anim. Breeding Genet. (9): 184.
  • Dickhoefer U, Hao J, Bösing BM, Lin L, Gierus M, Taube F, Susenbeth A (2014). Feed intake and performance of sheep grazing semiarid grassland in response to different grazing systems. Rangeland Ecol. Manage. 67(2): 145-153.
  • Elphick BL (1932). The detection and estimation of modulated fiber in New Zealand Romney Fleeces. J. textile Inst. 23(12): 367-385.
  • Golombeski GL, Kalscheur KF, Hippen AR, Schingoethe DJ (2006). Slow-release urea and highly fermentable sugars in diets fed to lactating dairy cows. J. Dairy Sci. 89 (11): 4395-4403.
  • Hamilton TS, Robinson WB, Johnson BC (1948). Further comparisons of the utilization of nitrogen of urea with that of some feed proteins by sheep. J. Anim. Sci. 7(1): 26-34.
  • Harris LE, Mitchell HH (1941). The value of urea in the synthesis of protein in the paunch of the ruminant, in maintenance. J. Nutr. 22: 167-182.
  • Harris LE, Mitchell HH (1941). The value of urea in the synthesis of protein in the paunch of the ruminant in growth. J. Nutr. 22: 183-196.
  • Hernandez PA, Mendozaa GD, Barcena JR, Plata FX, Martinez JA, Lee HA (2011). Effect of exogenous fibrolytic enzyme and slow release urea in finishing rations for lamb. J. App. Ani. Res. 39(2): 104-107.
  • Highstreet A, Robinson PH, Robison J, Garrett JG (2010). Response of Holstein cows to replacing urea with a slowly rumen released urea in a diet high in soluble crude protein. Livest. Sci. 129(1-3): 179-185.
  • Hue KT, Van DTT, Ledin I (2008). Effect of supplementing urea treated rice straw and molasses with different forage species on the performance of lambs. Small Ruminant Res. 78(1-3): 134-143.
  • Hynd PI, Schlink AC, Phillips PM, Scobie DR (1986). Mitotic activity in cells of the wool follicle bulb. Aust. J. Biol. Sci. 39(4): 329-340.
  • Johnson BC, Hamilton TS, Mitchell HH, Robinson WB (1942). The relative efficiency of urea as a protein substitute in the ration of ruminants. J. Anim. Sci. 1(3): 236-245.
  • Johnson BC, Hamilton TS, Robinson WB, Garey JC (1944). On the mechanism of non-protein nitrogen utilization by ruminants. J. Anim. Sci. 3(3): 287-298.
  • Kaur H, Arora SP (1995). Dietary effects on ruminant livestock reproduction with particular reference to protein. Nut. Res. Rev. 8(1): 121-136.
  • Kertz AF (2010). Urea feeding to dairy cattle: A historical perspective and review. Prof. Anim. Sci. 26 (3): 257-272.
  • Knox MR, Steel JW (1999). The effects of urea supplementation on production and parasitological responses of sheep infected with Haemonchus contortus and Trichostrongylus colubriformis. Vet. Parasitol. 83(2): 123-135.
  • Lizarazo AC, Mendoza GD, Ku J, Melgoza LM, Crosby M (2014). Effects of slow-release urea and molasses on ruminal metabolism of lambs fed with low-quality tropical forage. Small Ruminant Res. 116(1): 28-31.
  • Liesegang A, Staub T, Wichert B, Wanner M, Kreuzer M (2008). Effect of vitamin-E supplementation of sheep and goats fed diets supplemented with polyunsaturated fatty acids and low in Se. J. Anim. Physiol. Anim. Nutr. 92(3): 292-302.
  • Lofgreen GP, Weir WC, Wilson JF (1953). Gains in weight, nitrogen retention and wool growth of lambs fed a ration containing urea supplemented with sodium sulfate. J. Anim. Sci. 12(2): 347-352.
  • Morand-Fehr P, Boyazoglu J (1999). Present status and future outlook of small ruminant sector. Small Ruminant Res. 34(3): 175-188.
  • Nawaz M, Meyer HH, Jadoon JK, Naqvi MA (1992). Results from adaptability trial of Rambouillet sheep and their crossbreeding with Kaghanis. Effects on ewe mating weight, wool production, litter size and lamb growth. Asian-Australas. J. Anim. Sci. 5(3): 481-485.
  • Nocek JE, Russell JB (1988). Protein and energy as an integrated system. Relationship of ruminal protein and carbohydrate availability to microbial synthesis and milk production. J. Dairy Sci. 71(8): 2070-2107.
  • Peirce AW (1951). The effect of the ingestion of urea on the rate of wool production by Merino sheep. Aus. J. Agric. Res. 2(4): 435-446.
  • Pinos-Rodriguez JM, Pena LY, Sergio S, Gonzalez-Munoz, Barcena R, Salem A (2010). Effects of a slow-release coated urea product on growth performance and ruminal fermentation in beef steers. Ital. J. Anim. Sci. 9(1): 16-19.
  • Rafiq M, Aujla KM, Abrar H, Ghuman AM, Beghum I (2013). Performance of rambouillet crossbred grazing on alpine pastures of Pakistan under transhumant system. Egypt. J. Sheep Goat Sci. 8(1): 189-199.
  • Saric T, Rogosic J, Tkalcic S, Zupan I, Sikic Z (2013). Increased intake of juniperus phoenicea L. by supplementation with barley and Optigen® in sheep. Ital. J. Anim. Sci. 12(2): 320-322.
  • Sarwar M, Shahzad MA, Nisa M (2010). Small ruminant production in Pakistan. Egypt. J. Sheep Goat Sci. 5(1): 17-26.
  • Taylor-Edwards CC, Hibbard G, Kitts SE, McLeod KR, Axe DE, Vanzant ES, Kristensen NB, Harmon DL (2009). Effects of slow-release urea on ruminal digesta characteristics and growth performance in beef steers. J. Anim. Sci. 87(1): 200-208.
  • Yeastes NTM (1965) Modern aspects of animal production, Butterworts, London, vii+371.
  • Tillman AD, Swift RW (1953). The utilization of ammoniated industrial by-products and urea by sheep. J. Anim. Sci. 12: 201-212.
  • Yirga H, Melaku S, Urge M (2011). Effect of concentrate supplementation on live weight change and carcass characteristics of Hararghe Highland sheep fed a basal diet of urea-treated maize stover. Livestock Res. Rural Dev. 23(12).