Effect of monensin sodium and yeast metabolites supplementation on reproductive performance of lactating Sahiwal cows

Introduction

Feed additives have become an important component of modern ruminant nutrition because of their ability to improve feed utilization, rumen fermentation, animal productivity and overall health status. Among the various nutritional interventions available, ionophores and yeastbased feed additives have received considerable attention owing to their beneficial effects on ruminal metabolism and production efficiency (Duffield et al., 2008; Habeeb, 2017) [8,11] . Monensin sodium is a polyether ionophore produced by Streptomyces cinnamonensis and is widely used in ruminant feeding systems to improve feed efficiency and animal performance (Duffield et al., 2008) [8] . Its primary mode of action involves selective inhibition of grampositive ruminal bacteria, resulting in increased propionate production and reduced methane and ammonia synthesis in the rumen (Russell and Strobel, 1989) [16] . Increased propionate production improves glucose availability and energy utilization, thereby reducing the negative energy balance commonly observed during early lactation (Duffield et al., 2008) [8] . Consequently, monensin supplementation has been associated with improved feed efficiency, nutrient utilization, milk production and reproductive performance in dairy cattle (Phipps et al., 2000; Ruiz et al., 2001; Duffield et al., 2008) [13,15,8] . In recent years, increasing concerns regarding the use of antibiotic feed additives and consumer demand for residue-free livestock products have stimulated interest in natural alternatives capable of improving animal productivity and health (El-Bordeny et al., 2019) [9] . Among these alternatives, yeast cultures and yeast metabolites derived from Saccharomyces cerevisiae have emerged as promising feed additives for ruminants (Desnoyers et al., 2009; Habeeb, 2017) [6,11] . Yeast supplementation positively influences rumen microbial ecology by stimulating cellulolytic bacterial growth, scavenging oxygen within the rumen, stabilizing ruminal pH and enhancing fibre digestion (Desnoyers et al., 2009; Habeeb, 2017) [6,11] . Furthermore, yeast products promote microbial protein synthesis and improve nutrient digestibility, resulting in enhanced feed utilization and animal performance (Habeeb, 2017) [11] . Several studies have reported improvements in dry matter intake, milk yield, milk composition and feed efficiency following supplementation with yeast culture products in dairy animals (Desnoyers et al., 2009; El-Bordeny et al., 2019) [6,9] . Apart from productive performance, yeast supplementation may also exert beneficial effects on reproductive efficiency. Improved nutrient availability, enhanced metabolic status and better ruminal fermentation are considered important factors contributing to earlier resumption of ovarian activity, shorter service periods and improved fertility in dairy animals (Desnoyers et al., 2009; El-Bordeny et al., 2019; Habeeb, 2017) [6,9,11] . El-Bordeny et al. (2019) [9] reported a reduction in the period to first oestrus and service period, along with improved fertility rate, in lactating buffaloes supplemented with yeast-based probiotics. Although monensin and yeast products differ in their mechanisms of action, both feed additives ultimately improve nutrient utilization and metabolic efficiency. Monensin primarily enhances energetic efficiency through increased ruminal propionate production, whereas yeast metabolites improve fibre degradation, microbial growth and ruminal stability (Duffield et al., 2008; Desnoyers et al., 2009) [8,6] . Consequently, both additives may contribute to improved productive and reproductive performance in dairy cattle. Sahiwal cattle represent one of the most important indigenous dairy breeds of India because of their adaptability, disease resistance and ability to maintain production under tropical climatic conditions. However, information regarding the influence of monensin sodium and yeast metabolites on reproductive performance of Sahiwal cows remains limited. Therefore, the present study was undertaken to evaluate the effect of dietary supplementation of monensin sodium and yeast metabolites on reproductive parameters, including first postpartum heat period, calving-to-conception interval and conception rate in lactating Sahiwal cows.

Materials and Methods

Experimental Site

The present investigation was conducted at the Bull Mother Experimental Farm (BMEF), College of Veterinary Science and Animal Husbandry, Anjora, Durg, Chhattisgarh, India. The region is located at an altitude of 317 m above mean sea level and experiences a tropical climate characterized by hot summers, moderate winters and seasonal monsoon rainfall.

Experimental Animals and Design

Eighteen lactating purebred Sahiwal cows in early lactation were selected from the institute herd and randomly allocated into three groups (n = 6 per group) based on parity and body weight. Prior to the initiation of the experiment, all animals were dewormed with fenbendazole (7.5-10 mg/kg body weight).

The experimental groups were as follows T 0 (Control): Basal diet only T 1: Basal diet + Monensin sodium (1 g/animal/day) T 2: Basal diet + Yeast metabolites (3 g/animal/day)

The feeding trial was conducted for a period of 90 days.

Feeding and Management

All experimental animals were maintained under identical housing and management conditions in a conventional double-row barn system with concrete flooring. The animals were fed a basal ration comprising green fodder, dry fodder and concentrate mixture according to the farm feeding schedule. The green fodder consisted mainly of Hybrid Napier, Sudan grass, Berseem and locally available grasses. In addition, animals were allowed grazing for approximately 4 h daily during the morning. Concentrate mixture was offered twice daily during milking. Fresh drinking water was made available ad libitum throughout the experimental period.

Reproductive Parameters

Reproductive performance of experimental cows was assessed using calving to first postpartum oestrus interval, calving to conception interval and conception rate.

Calving to First Postpartum Oestrus Interval

All cows were observed twice daily (morning and evening) for behavioral signs of oestrus following parturition. The interval between calving and the first observed postpartum oestrus was recorded and expressed in days.

Calving to Conception Interval

The interval from calving to successful conception was recorded for each animal using farm reproductive records and expressed in days.

Conception Rate

Conception rate was calculated as the percentage of inseminated cows that conceived during the experimental period according to the following formula: Conception Rate (%) = (Number of cows conceived / Number of cows inseminated) × 100 Pregnancy status was confirmed through routine pregnancy diagnosis records maintained at the farm.

Statistical Analysis

Data were analysed using SPSS statistical software. Treatment means were compared by one-way analysis of variance (ANOVA) as described by Snedecor and Cochran. Differences were considered statistically significant at p < 0.05.

Results

Reproductive Performance

The effect of dietary supplementation of monensin sodium and yeast metabolites on reproductive performance of lactating Sahiwal cows is presented in Table 1.The mean calving to first postpartum oestrus interval was 157.20 ± 22.37, 153.33 ± 18.01 and 120.33 ± 11.91 days in the control, monensin-supplemented and yeast metabolite-supplemented groups, respectively. Although cows supplemented with yeast metabolites exhibited a shorter postpartum oestrus interval compared to the control and monensin groups, the differences among treatments were not statistically significant (P = 0.236). Similarly, the mean calving to conception interval was 166.00 ± 21.22 days in the control group, 188.50 ± 6.81 days in the monensin group and 123.33 ± 14.76 days in the yeast metabolite group. Numerically, cows receiving yeast metabolites showed a reduced calving to conception interval compared to the control and monensin-supplemented cows. However, the variation among groups was statistically nonsignificant (P = 0.178). The conception rate was 50.00 ± 21.22, 66.66 ± 21.08 and 50.00 ± 21.22 per cent in the control, monensin and yeast metabolite groups, respectively. Although the monensinsupplemented group recorded a higher conception rate than the other groups, no significant treatment effect was observed (P = 0.739). Overall, supplementation of monensin sodium and yeast metabolites did not significantly influence the reproductive parameters studied. Nevertheless, yeast metabolite supplementation tended to improve reproductive efficiency by reducing the calving to first postpartum oestrus interval and calving to conception interval, whereas monensin supplementation showed a numerical improvement in conception rate.

Discussion

Reproductive efficiency is an important determinant of productivity and profitability in dairy cattle, as it directly affects calving interval, lifetime milk yield and overall herd performance. In the present study, supplementation of monensin sodium and yeast metabolites resulted in numerical improvements in reproductive parameters, although the differences among treatment groups were statistically nonsignificant (P>0.05). The observed numerical improvements may be attributed to enhanced nutrient utilization, improved rumen fermentation and better metabolic status of supplemented animals. The first postpartum heat period was numerically reduced in cows supplemented with yeast metabolites (120.33 ± 11.91 days) compared to the control (157.20 ± 22.37 days) and monensin-supplemented groups (153.33 ± 18.01 days). Earlier resumption of ovarian activity following calving is generally associated with improved energy balance and nutrient availability during early lactation. Yeast supplementation is known to stimulate rumen microbial activity, improve fiber digestion and enhance volatile fatty acid production, thereby increasing nutrient availability to the host animal. Improved energy status may facilitate earlier recovery of ovarian function and resumption of cyclicity after calving. Similar observations were reported by Desnoyers et al. (2009) [6] , who concluded that yeast supplementation improved reproductive performance and metabolic efficiency in dairy cows.

The calving-to-conception interval was also numerically lower in the yeast metabolite-supplemented group (123.33 ± 14.76 days) than in the control (166.00 ± 21.22 days) and monensin-supplemented groups (188.50 ± 6.81 days). A shorter calving-to-conception interval reflects improved reproductive efficiency and reduced days open. The beneficial effect of yeast supplementation may be associated with improved ruminal fermentation, enhanced microbial protein synthesis and improved nutrient utilization, which contribute to better reproductive performance. Similar findings have been reported by Habeeb et al. (2017) [11] , who observed improvements in reproductive traits following supplementation with yeast-based feed additives. Monensin supplementation did not reduce the postpartum heat period or calving-to-conception interval compared to the control group; however, cows receiving monensin exhibited a numerically higher conception rate (66.66%) than control and yeast-supplemented cows (50.00%). Monensin is known to alter ruminal fermentation by increasing propionate production and improving feed efficiency. Enhanced propionate production increases glucose availability and improves energy balance, which may positively influence reproductive function and conception success. Similar findings were reported by Duffield et al. (2008) [8] , who observed improved reproductive performance in monensinsupplemented dairy cows. Phipps et al. (2000) [13] and Ruiz et al. (2001) [15] also reported beneficial effects of monensin on reproductive efficiency through improvements in metabolic status and energy utilization. Although conception rate was numerically greater in the monensin-supplemented group, the differences among treatment groups were statistically non-significant (P>0.05). The absence of significant differences in reproductive traits may be attributed to the limited number of experimental animals, individual animal variation and the relatively short duration of supplementation. Similar non-significant effects of dietary additives on reproductive performance have been reported by Dann et al. (2000) and Benchaar et al. (2008), who observed numerical improvements in reproductive traits without significant treatment effects. Overall, the findings of the present study indicate that supplementation of yeast metabolites tended to improve reproductive efficiency by reducing the first postpartum heat period and calving-to-conception interval, whereas monensin sodium supplementation showed a tendency to improve conception rate. However, these improvements were not statistically significant under the conditions of the present experiment.

Conclusion

The present study demonstrated that dietary supplementation of monensin sodium and yeast metabolites had no significant effect on reproductive parameters of lactating Sahiwal cows. However, yeast metabolite supplementation numerically reduced the calving to first postpartum oestrus interval and calving to conception interval, indicating a tendency towards improved reproductive efficiency. Monensin sodium supplementation resulted in a numerically higher conception rate compared to the control group. Although the observed improvements were not statistically significant, the findings suggest that both feed additives may positively influence reproductive performance through improved nutrient utilization and metabolic efficiency. Further studies involving a larger number of animals and a longer experimental period are recommended to validate these effects.

Acknowledgement

AcknowledgmentsThe authors are thankful to the Dean, College of Veterinary Science and Animal Husbandry, Anjora, Durg, for providing facilities to conduct this research.

References

1. Allbrahim RM, Crowe MA, Duffy P, O'Grady L, Beltman ME, Mulligan FJ. The effect of body condition at calving and supplementation with Saccharomyces cerevisiae on energy status and some reproductive parameters in early lactation of dairy cows. Animal Reproduction Science. 2010;121:63-71.
2. Arieli A, Dicken U, Dagoni I, Spirer Y, Zamwel S. Production and health of cows given monensin prepartum and a high-energy diet postpartum. Journal of Dairy Science. 2008;91(5):1845-1851.
3. Bailey CR, Goetsch AL, Hubbell DS, Rosenkrans CF. Effects of monensin on beef cow reproduction. Canadian Journal of Animal Science. 2007;88(1):113-115.
4. Beckett S, Lean I, Dyson R, Tranter W, Wade L. Effects of monensin on the reproduction, health, and milk production of dairy cows. Journal of Dairy Science. 1998;81(6):1563-1573.
5. Chaucheyras-Durand F, Walker ND, Bach A. Effects of active dry yeasts on the rumen microbial ecosystem: Past, present and future. Animal Feed Science and Technology. 2008;145(1-4):5-26.
6. Desnoyers M, Giger-Reverdin S, Bertin G, DuvauxPonter C, Sauvant D. Meta-analysis of the influence of Saccharomyces cerevisiae supplementation on ruminal parameters and milk production of ruminants. Journal of Dairy Science. 2009;92(4):1620-1632.
7. Duffield TF, Leslie KE, Sandals D, Lissemore K, McBride BW, Lumsden JH, et al. Effect of a monensincontrolled release capsule on cow health and reproductive performance. Journal of Dairy Science. 1999;82(11):2377-2384.
8. Duffield TF, Rabiee AR, Lean IJ. A meta-analysis of the impact of monensin in lactating dairy cattle. Part 1. Metabolic effects. Journal of Dairy Science. 2008;91(4):1334-1346.
9. El-Bordeny NE, Abdou A, Abo-Eid H, Abdo MM, Abdel-Gawad RMA. Effect of yeast-based probiotics supplementation on productive and reproductive performance of lactating buffaloes. Egyptian Journal of Nutrition and Feeds. 2019;22(2):33-44.
10. Erasmus LJ, Robinson PH, Ahmadi A, Hinders R, Garrett JE. Influence of prepartum and postpartum supplementation of a yeast culture and monensin, or both, on ruminal fermentation and performance of multiparous dairy cows. Animal Feed Science and Technology. 2005;122(3-4):219-239.
11. Habeeb AAM. Importance of yeast in ruminants feeding on production and reproduction. Ecology and Evolutionary Biology. 2017;2(4):49.
12. Nocek JE, Holt MG, Oppy J. Effects of supplementation with yeast culture and enzymatically hydrolyzed yeast on performance of early lactation dairy cattle. Journal of Dairy Science. 2011;94(8):4046-4056.
13. Phipps RH, Wilkinson JID, Jonker LJ, Tarrant M, Jones AK, Hodge A. Effect of monensin on milk production of Holstein-Friesian dairy cows. Journal of Dairy Science. 2000;83:2789-2794.
14. Poppy GD, Rabiee AR, Lean IJ, Sanchez WK, Dorton KL, Morley PS. A meta-analysis of the effects of feeding yeast culture produced by anaerobic fermentation of Saccharomyces cerevisiae on milk production of lactating dairy cows. Journal of Dairy Science. 2012;95(10):60276041.
15. Ruiz R, Albrecht GL, Tedeschi LO, Jarvis G, Russell JB, Fox DG. Effect of monensin on the performance and nitrogen utilization of lactating dairy cows consuming fresh forage. Journal of Dairy Science. 2001;84(7):17171727.
16. Russell JB, Strobel H. Effect of ionophores on ruminal fermentation. Applied and Environmental Microbiology. 1989;55(1):1-6.
17. Snedecor GW, Cochran WG. Statistical methods. 8th ed. Ames (IA): Iowa State University Press; 1994.
18. Tallam SK, Duffield TF, Leslie KE, Bagg R, Dick P, Vessie G, et al. Ovarian follicular activity in lactating Holstein cows supplemented with monensin. Journal of Dairy Science. 2003;86:3498-3507.
19. Uyeno Y, Akiyama K, Hasunuma T, Yamamoto H, Yokokawa H, Yamaguchi T, et al. Impact of supplementing an active dry yeast product on rumen microbial community structure and subsequent rumen fermentation in lactating cows during the mid-to-late lactation phase. Animal Science Journal. 2017;88:119124.
20. Yuan K, Liang T, Muckey MB, Mendonça LGD, Hulbert LE, Elrod CC, et al. Yeast product supplementation modulated feeding behavior and metabolism in transition dairy cows. Journal of Dairy Science. 2015;98(1):532540.