An experiment aimed to observe the effects of supplementation of selenium yeast and/or vitamin E on their growth, nutrient utilization and immune response. Twenty four male kids (2-3 months) were divided into Group I (control; without any supplementation), II (0.3 mg selenium kg-1DM as Selenium yeast), III (100 mg of vitamin E as DL-α-tocopheryl acetate) and IV (combination of II and III) along with a basal diet (concentrate mixture and oat straw) to meet their nutrient requirement for 180 days. No significant (P>0.05) effect of selenium yeast and/or vitamin E supplementation on average daily gain, digestibility of nutrients, retention of nitrogen, calcium and phosphorus. Highest (P<0.05) humoral immunity was seen in the group IV. It may be concluded that supplementation of 0.3 ppm Se as selenium yeast and 100 mg of vitamin E improved the immune response of the kids, without affecting growth and digestibility of nutrients.
Selenium (Se) and vitamin E play significant role in improving the immunity, antioxidant status, and reproduction in animals. Several reproductive problems like retained placenta, abortion, premature birth, cystic ovaries, metritis, and delayed conception were reported due to deficiency of vitamin E and Se (Surai, 2002). Selenium is required for the development and expression of non-specific humoral and cell mediated immune responses. Nicholson et al. (1991) observed improved weight gain and gain: feed ratio in dairy and beef calves fed 1mg Se kg-1 DM supplemented diet over control (0.26mg Se kg-1 DM) group. Studies conducted in our laboratory have shown significant improvement in growth performance due to Se supplemented diet in lambs (Kumar et al., 2009a) and improved immune status in buffalo calves (Mudgal et al., 2012). There are different sources of Se supplementation viz. inorganic (sodium selenite or sodium selenate) and organic sources (selenium yeast) used in animals feeds (Sethy et al., 2014 a, b; 2015). Generally, Se is supplemented in animal feeds as inorganic salts. However, studies have shown that organic Se is better absorbed and utilized as compared to inorganic Se (Guyot et al.,2007, Sethy et al., 2014 b). A diet deficient in vitamin E may increase Se requirement of the animal. Little work has been done to explore the effect of selenium yeast (organic selenium) and/or vitamin E supplementation on the performance of goats. Thus, the objective of the present study was to find out the effect of selenium yeast and/or vitamin E supplementation on growth, nutrient utilization and immunity in male kids.
Material and Methods
Animal’s Management and Feeding
Present experiment was approved by the “Committee for the Purpose of Control and Supervision of Experiments on Animals” (CPCSEA), India, and was conducted on 24 male kids (Capra hircus; about 2-3 months of age, average live weight 6.8±0.20kg) procured from Sheep and Goat Farm of Indian Veterinary Research Institute, Izatnagar, India. These animals were adapted to the experimental diet comprising of concentrate mixture and oat straw for a period of one month during which they were treated against ecto and endo parasites and subsequently, at regular intervals as well. All the kids were vaccinated against foot and mouth disease and peste des petits of ruminants (PPR). These animals were distributed into four different groups of six kids each on the basis of their body weights following randomized block design, and were kept in a well-ventilated shed with individual feeding and watering arrangements. Kids in all the four groups were fed on concentrate mixture and oat straw to meet their nutrient requirements for 50 g daily weight gain (NRC, 2007). The concentrate mixture consisted of (%) crushed maize grain 30, soybean meal 37, wheat bran 30, mineral mixture 2 and common salt 1.Treatments were: group I (control), without any supplementation, group II supplemented with 0.3 ppm Se as selenium yeast, group III supplemented with 100 mg vitamin E as DL-α-tocopheryl acetate /kid/day (Impextraco, Belgium) and group IV supplemented with both 0.3 ppm organic Se and 100 mg vitamin E through the concentrate mixture. Oat straw was provided to the animals after total consumption of concentrate mixture. All the kids were offered about 100 g of the available green berseem (Trifolium alexandrium) fodder once a week to meet their vitamin A requirements. Clean and fresh drinking water was provided twice a day to all the animals. This feeding practice lasted for 180 days.
Body Weight Change
All the kids were weighed after every fortnight in the morning before offering them any feed or water throughout the experimental period to assess their growth rate.
A metabolism trial was conducted to determine the digestibility and intake of nutrients, balance of nitrogen (N), calcium (Ca) and phosphorus (P) after 100 days of experimental feeding in metabolism cages equipped with individual feeding, watering, separate urine and feces collection facilities. After adapting the animals for 3 days in the metabolic cages, actual collection of feces and urine was done for 6 days. Weighed amount of feeds were offered and residue was collected at a fixed time daily in the morning, quantified and a representative sample was collected and analyzed daily for dry matter content. Total feces voided by individual animal during 24 h was collected into a pre-weighed plastic bucket, and weighed at a fixed time (9.30 h) daily. For DM estimation, suitable aliquots of feces were taken, pooled and kept in polythene bags for further analysis. A suitable aliquot of feces was also taken daily into a glass bottle containing dilute (1:5) sulphuric acid for the estimation of nitrogen. Urine excreted in 24 h was also collected in plastic bottles and measured daily at fixed time (9.30 h). A suitable aliquot of urine was taken daily and pooled into Kjeldahl flask containing 40 ml commercial sulphuric acid for nitrogen estimation. A separate aliquot of urine was taken, pooled, and preserved for the estimation of calcium and phosphorus. The pooled dried samples of feeds and feces were ground in a Willey mill to pass through 1 mm sieve and stored in airtight bottles for further analysis.
Feeds and feces samples were analyzed for proximate principles (AOAC, 2000) and fiber (Van Soest et al., 1991). For the estimation of minerals feed and feces samples were ashed in a muffle furnace at 550-6000C for 3 h and HCl extract was prepared after dissolving the ash in 0.1N HCl. Similarly, urine samples were ashed in muffle furnace after drying the urine in silica crucibles on a hot plate and HCl extract was prepared. The HCl extract thus prepared was used for the estimation of calcium (Talapatra et al., 1940) and phosphorus (AOAC, 2000).
Humoral Immune Response
After 120 days of experimental feeding, all the kids were inoculated intramuscularly with 2 ml of Pasteurella multocida oil adjuvant vaccine (Biological Products Division, Indian Veterinary Research Institute, Izatnagar, India). About 3ml blood was collected from each animal through jugular vein puncture observing all aseptic precautions in the morning (before watering and feeding) on the day of vaccine inoculation (0 day) and subsequently at 7 days interval up to 28 days. Blood samples were centrifuged at 700 x g for 15 min to separate out serum, which was stored in plastic vials (2 ml) at -20ºC for further serological analysis by ELISA. The antigen for ELISA was prepared by disrupting the pure culture of Pasteurella multocida (P52 strain) using 100-W ultrasonic disintegrator at 6μ amplitude peak to peak for 30 min and used for ELISA (Almeida et al., 1979). Concentration of protein was measured (Dumas et al., 1971) and adjusted to 1μg/5μl of sonicated antigen for ELISA.
The Data from biological samples were statistically analyzed using SPSS (1996) computer package and are briefed as follows. Generalized linear Model ANOVA was used on the data of body weight gain, digestibility of nutrients and balance of nitrogen, calcium and phosphorus; and Duncan’s multiple range test was used to conduct post hoc test. Repeated measures ANOVA was performed on antibody mediated immune response. Greenhouse- Geiser adjusted significance test was applied to compare the values obtained in different hours/days of experiment according to Little et al. (1998).
Results and Discussion
The chemical composition of the basal feed offered to experimental kids is presented in Table 1. The crude protein content in concentrate mixture and oat straw and was 20.6 and 4.3 %, respectively. α-tocopherol concentration in concentrate mixture and oat straw was 13.15 and 2.0 mg kg-1 feed, respectively.
Table1: Chemical composition (%DM basis) of concentrate mixture and oat straw fed to kids
|Nutrients||Concentrate Mixture||Oat Straw|
|Neutral detergent fiber||34.50||78.30|
|Acid detergent fiber||11.60||57.10|
|Selenium, mg kg -1||0.12||0.11|
|α-tocopherol, mg kg -1||13.75||1.90|
Growth Performance and Feed: Gain Ratio
Total body weight gain, average daily gain (ADG, g/d) and feed: gain ratios are presented in Table 2. Results of the present study revealed no significant effect of selenium yeast and/or vitamin E supplementation on growth performance as ADG (g d-1) was similar (P>0.05) in all the 4 groups of kids.
Table 2: Effect of selenium and vitamin E supplementation on weight gain and feed: gain ratio in kids
|Item||Group||SEM (±)||P value|
|Initial body weight, Kg||6.74||6.67||6.68||6.63||0.10||0.52|
|Final body weight ,Kg||13.39||12.89||13.33||12.79||0.24||0.28|
|Body weight gain ,Kg||6.65||6.22||6.65||6.16||0.16||0.45|
|Average daily gain, g||36.94||34.55||36.91||34.22||0.89||0.31|
|Average DMI, g d-1||327.30||321.30||322.50||315.30||5.38||0.33|
|Feed: gain ratio||8.86||9.29||8.73||9.21||0.42||0.11|
Previous reports in male buffalo calves (Mudgal et al., 2007) and finishing lambs (Dominguez-Vara et al., 2009) are in accordance with the current results where no effect was observed on their growth rate by supplementation of 0.3 mg Selenium yeast kg-1 DM. Turner et al. (2002) in lambs and Cusack et al. (2005) in calves observed no effect of vitamin E supplementation on their average daily gain. Supplementation of vitamin E (300 IU) or Se (0.3 ppm) or both (300 IU vitamin E and 0.3 ppm Se) in the diet of buffalo calves had no effect on total body weight gain and ADG (Shinde et al., 2008) which supports the present results. Contrary to this, Nicholson et al. (1991) in calves and Kumar et al. (2009a) reported an increase in growth rate in organic Se-supplemented lambs as compared to control lambs. In the present experiment, supplementation of Se and/or vitamin E had no effect on feed conversion efficiency of the kids as feed: gain ratio was comparable (P>0.05) among the four groups. Contrary to our findings, researchers have reported significantly higher feed conversion efficiency in Se-supplemented dairy and beef calves (Nicholson et al., 1991) as well as in guinea pigs (Chaudhary et al., 2010). However, Mudgal et al. (2007) did not find any significant effect on feed conversion efficiency in male buffalo calves supplemented with 0.3mg Se which supports present results. Shinde et al. (2008) also did not find any effect on feed: gain ratio in buffalo calves given vitamin E (300 IU) or Se (0.3 ppm) or both (300 IU vitamin E and 0.3 ppm Se).
Nutrients Intake and their Digestibility
Data of dry matter intake (DMI, g d-1) and digestibility (%) of different nutrients in different groups of kids are presented in Table 3. Results revealed that the intake of DM and digestibility of DM, OM, CP, EE, NDF, ADF, cellulose and hemicelluloses were statistically (P>0.05) similar in all 4 groups of kids, which indicated that supplementation of selenium yeast (0.3 mg kg-1 diet ), vitamin E (100 mg) or both had no effect on nutrients intake and their digestibility in kids.
Table 3: Nutrients intake and their digestibility (%) in kids
|Attributes||Group||SEM (±)||P value|
|Total DM intake||343.40||340.80||342.50||340.00||18.87||0.32|
On the contrary, Secrist et al. (1997) reported a positive effect on DMI and its digestibility in crossbred steers due to vitamin E supplementation and Hemken et al. (1998) observed significant increase in the daily DMI in the selenium supplemented cows than control. Kumar et al. (2009b) also did not find any effect of organic Se supplementation on DMI and its digestibility in lambs and Rajeesh et al. (2007) also did not find any difference in DMI due to vitamin E supplementation in buffalo calves. Our results corroborated well with the observations of Shinde et al. (2008) who reported that supplementation of vitamin E (300 IU) or Se (0.3mg kg-1DM) or both (300 IU vitamin E and 0.3mg Se kg-1DM) in the diet of buffalo calves had no effect on DMI and nutrient digestibility. Digestibility of CP, EE, NDF, ADF, cellulose and hemicellulose were also found to be similar (P>0.05) in all the four groups, suggesting that supplementation of selenium yeast (0.3mg kg-1DM) and/or vitamin E (100 mg) had no effect on digestibility of these nutrients. Similarly, Nicholson et al. (1991) in beef cattle and Mudgal et al. (2007) in buffalo calves did not observe any difference in the digestibility of these nutrients with selenium supplementation. Supplementation of 20 and 40 mg vitamin E kg-1 DM to buffalo calves for 120 days had no effect on digestibility of CP, EE, NDF, ADF, hemicelluloses and cellulose (Dass et al., 2009). Supplementation of vitamin E (300 IU) or Se (0.3mg kg-1DM ) or both (300 IU vitamin E and 0.3mg Se kg-1DM) in the diet of buffalo calves also had no effect on digestibility of CP, EE, NDF, ADF, hemicelluloses and cellulose (Shinde et al., 2008).
Data of nitrogen, calcium and phosphorus intake, their excretion through feces, urine and their retention in different groups of kids are presented in Table 4. There was no statistical (P>0.05) significant difference in the intake, excretion through feces and urine and retention of nitrogen, calcium and phosphorus was observed in these 4 groups.
Table 4: Intake and balance of nitrogen, calcium and phosphorus (g d-1) in different groups of kids
|Attributes||Group||SEM (±)||P value|
|Balance as % of intake||53.00||54.30||58.50||55.50||3.17||0.14|
|Balance as% of intake||33.33||33.33||34.15||34.88||2.10||0.23|
|Balance as% of intake||30.00||34.21||30.00||31.58||1.85||0.09|
Likewise, the absorption of nitrogen, calcium and phosphorus in 4 groups of kids was also statistically alike. Samanta and Dass (2006) in crossbred calves and Rajeesh et al. (2007) in buffalo calves also reported same trend with different levels of vitamin E. Organic Se supplementation also could not affect the intake and balance of N, Ca and P in lambs (Kumar et al., 2009b). Supplementation of vitamin E (300 IU) or Se (0.3mg Se kg-1DM) or both (300 IU vitamin E and 0.3mg Se kg-1DM) in the diet of buffalo calves had no effect on N, Ca and P intake, their excretion and retention (Shinde et al., 2008).
Humoral Immune Response
Antibody mediated immune response of the kids enhanced significantly (P<0.05) by the supplementation of 0.3mg Se kg -1 DM as selenium yeast or 100 mg vitamin E or both. But the response was observed maximum in the group IV where both Se and Vitamin E were supplemented (Table 5). Stabel et al. (1989) in calves and Nicholson et al. (1993) in beef cattle did not find any effect of Se supplementation on immunological response of animals, which was probably due to high amount of Se in their basal diet (0.41mg/kg DM). Supplementation of 0.3 ppm organic-Se to Rambouillet sheep for 95 days had no effect on plasma IgG concentration (Dominguez-vara et al., 2009).
Table 5: ELISA antibody titer in different groups of kids vaccinated with P. multocida oil adjuvant vaccine
|Group||Blood collection (days)||Mean*||SEM||P value|
|0||7||14||21||28||G||P||G x P|
a,b,c Means bearing different superscripts in a column differ significantly (P< 0.05)
However, Kumar et al. (2009b) in sheep and Mudgal et al. (2012) in buffalo calves observed higher antibody titer in Se-supplemented animals than control. Similarly, Reddy et al. (1987) and Samanta et al. (2008) reported increased humoral immunity in vitamin E supplemented calves than control calves. With supplemented with vitamin E (300 IU) or Se (0.3 ppm) or both (300 IU vitamin E and 0.3 ppm Se), higher antibodies against Pasteurella multocida P52 in buffalo calves was reported than control (Shinde et al., 2007).
It may be concluded that supplementation of 0.3 ppm selenium as selenium yeast and 100 mg of DL-α-tocopheryl acetate improved the immunity of the kids without having any effect on their growth and digestibility of nutrients, but combination of both Vitamin E and Selenium as selenium yeast has better effect in strengthening the immunity of the animals.
First author is thankful to Indian Council of Agricultural Research, Krishi Bhawan, New Delhi, India, for providing financial assistance in the form of senior Research Fellowship. Authors are thankful to the Director, Indian Veterinary Research Institute, Izatnagar, India for providing the necessary facilities to carry out this work.