Effect of rumen protected choline (RPC) on milk yield and composition in crossbred dairy cows

Introduction

Choline, also known as trimethyl ethanolamine, is an essential component of mammalian diets as it is required for normal function of cells (Swartz et al., 2022) [9] . Choline is a critical component for synthesis of phospholipids and neurotransmitters, it supports structural integrity and signaling roles in cell membranes, influences cholinergic neurotransmission and cognition, and it is a major source for methyl-groups via betaine for methylation pathways. The dietary choline, betaine, methionine, folic acid, Vitamin B 12 all contribute to the body choline content. Particularly in early lactation, choline enhances milk fat synthesis and mitigates fatty liver syndrome post-parturition, a condition linked to elevated hepatic lipid accumulation and compromised reproductive performance (Cooke et al., 2007) [2] . Dietary choline is degraded rapidly by the rumen microorganisms (Neill, 1979; Sharma and Erdman, 1989) [9,15] ; hence, supplementation with choline is not an effective way to increase choline supply. Therefore, rumen-protected forms of choline have been developed to deliver choline to the small intestine for absorption (Elek et al., 2008) [3] . The various protein sources are rich sources of choline but due to rumen degradability (85-95%) the animal will depend on its endogenous choline synthesis for their metabolic needs. Hence, there is need for use of protected choline in the diet of dairy animals for better health and productivity. Microencapsulation is used to protect a substance from degradation in the rumen. Feeding choline in this form not only meets the requirement of choline but also reduces the requirement of methionine and lysine as these two amino acids involved in the endogenous synthesis of choline. Studies demonstrate that RPC supplementation alleviates fatty liver in transition cows, elevates milk yield, fat, and protein percentages, and improves overall productivity (Hartwell et al., 2000; Zahra et al., 2006) [6,21] . Despite these benefits, evidence in crossbred dairy cows particularly in smallholder systems remains limited, especially concerning costeffectiveness amid fluctuating input costs. The present study investigates the effects of RPC supplementation in crossbred dairy cows, with the following objectives: (i) to evaluate its impact on milk yield and composition, and (ii) to assess its cost-effectiveness.

Materials and Methods

This experiment was carried out in cattle unit of Livestock farm complex, Madhavaram Milk Colony, Chennai-51 (Geographic coordinates: 1.15° N 80.24°E). Ten early lactating crossbred cows were selected from cattle section of LFC for this experiment. The length of the experimental period was 35 days. During the pre-supplementation period of initial 14 days, the animals were fed with basal diet without rumen protected choline (RPC). Then, during the post supplementation period of next 21 days, they were fed with basal diet along with 20 g rumen protected choline. The animals were housed in well-ventilated sheds, and maintained as per scientific managemental conditions. The animals were fed with basal diet comprising concentrates and green, dry roughages depending upon their body weight and level of production as per NRC (2001) [10] . The concentrate diet was procured from Central feed technology unit (CFTU), a constituent unit of Tamil Nadu Veterinary and Animal Sciences University, Kattupakkam and green, dry roughages were cultivated at LFC. The rumen protected choline was procured from Kemin Industries South Asia Pvt. Ltd, Chennai. The experimental animals had free access to clean, wholesome drinking water.

The animals were fed with concentrate twice daily, in the morning and in the afternoon before milking. Roughage was fed in three divided lots every day to ensure minimum wastage. The rumen protected choline was top dressed along with concentrate feed at the rate of 20g/animal/day for 21 days. Individual data on milk produced was recorded throughout the experiment. Data on milk yield of individual animal was recorded daily at morning and evening throughout the experimental period. Milk samples were collected and analysed for its fat and solids not fat (SNF) content by using EKOMILK ® digital milk analyser. The cost effectiveness of rumen protected choline feeding for producing per litre of milk was calculated using the data on total milk yield and milk composition during the experimental period.

The data on mean daily milk yield, fat and solids not fat (SNF) content were analyzed statistically (Snedecor and Cochran, 1994) [17] and the comparison of means was done using IBM Statistical Production and Service Solutions (SPSS), version 20.0.

Results and Discussion

Data on milk yield, fat and solid not fat (SNF) contents are presented in Table 2. The mean milk production (litres) pre rumen protected choline supplementation period was 4.93±0.30, and post rumen protected choline supplementation period was 5.05±0.33. There was statistically no significant difference in milk production due to RPC supplementation. But the milk fat content was improved significantly (p<0.05) by RPC. The mean milk fat percentage pre rumen protected choline supplementation was 4.67±0.08, and post rumen protected choline supplementation was 4.81±0.10. Similar to milk yield, the solid not fat (SNF) content had no significant difference statistically pre and post RPC supplementation. The SNF values before and after RPC supplementation was 7.51±0.07 and 7.52±0.09, respectively. [11] reported no significant difference in milk yield of crossbred lactating cows supplemented with 54 g/head/day RPC (16.93±1.57 kg/day) mixed with the basal ration when compared with the control (15.38±0.88 kg/day). Neelima et al. (2021) [8] found that supplementation of rumen protected choline @ 20 g/animal in early lactating cows had no significant difference (p>0.05) in milk yield. These results were in accordance with those of the present study. Milk yield was not significantly improved in the present study which may be because the animals selected for the experiment were only medium producers rather than high yielders, length of treatment period and also variations in stages of lactation. On contrary, several authors reported that supplementation of RPC had positive effect on milk yield of lactating cows. Erdman and Sharma (1991) [4] fed Holstein cows 0, 0.078, 0.156, and 0.234% RPC and found that added choline resulted in a linear increase in 3.5% FCM and feeding 0.156 and 0.234% choline increased FCM by 2.4 and 1.7 kg/day, respectively, over the control. Pinotti et al. (2001) [13] , who found that cows consuming 20 g/day RPC produced 3.5 kg/day more milk than the controls. Zahra et al. (2006) [21] reported that Holstein cows received 56 g/day of RPC produced on average 1.2 kg/day more milk yield through 60 days compared with those not receiving RPC supplementation. Guretzky et al. (2006) [5] fed Holstein and Jersey cows diets which were top dressed once daily with 60 g of RPC product and found that daily yield of 3.5% FCM increased by 2 kg/day compared with the control group. Rumen-protected choline supplementation in lactating Friesian cows led to increased milk yield by 1.32 and 2.24 kg/head/day or 8.75 and 14.85%, for 15 and 30 g RPC compared with un-supplemented RPC, respectively (p<0.05) (Mohsen et al., 2011) [7] The dietary rumen protected choline contributes insignificantly to the choline body pool. Choline facilitates phospholipid synthesis for lipid absorption and transport to the mammary gland, thereby favouring milk fat synthesis. Mohsen et al. (2011) [7] observed that the content of fat was increased significantly (p<0.05) with RPC supplementation. Neelima et al. (2021) [8] found that supplementation of rumen protected choline @ 20g/animal in early lactating cows had significant improvement (p<0.05) in milk fat content fed along with rumen protected methionine. These results were in accordance with the results obtained in the present study.

On the other hand, several researchers could not observe any significant effect on milk fat when animals fed with RPC. Piepenbrink and Overton (2003) [12] observed that increase in yields of milk fat of Holstein cows was fed treatments consisting of 0, 45, 60, or 75 g/d of a rumen-protected choline (RPC). Guretzky et al. (2006) [5] showed that cows fed RPC had increased milk fat, total solids contents and yield. Xu et al. (2006) [20] reported that supplemented RPC at various dose rates (0, 30, 60 and 90 g/d/head) to dairy cattle and found no significant difference in milk composition. Elek et al. (2008) [3] found that milk fat content was not altered by RPC supplementation in Holstein cows, but fat yield was increased by 0.10 kg/day as a consequence of higher milk yield in the RPC-treated group. Likewise, Baldi et al. (2011) [13] observed no difference in milk fat and protein contents when RPC was fed @ 4 g/d in goats during experimental period extending from 4 weeks prepartum to 4 weeks postpartum. Similarly, Suksombat et al. (2012) [18] also did not find any significant difference in milk composition after supplementation of 0, 20 and 40 g RPC/d to dairy cattle. Pawar et al. (2015) [11] reported no significant difference in milk fat content of crossbred lactating cows supplemented RPC.

The mean solid not fat content (percentage) of lactating cross bred cows fed pre and post rumen protected choline supplementation was 7.51±0.07 and 7.52±0.09 respectively (Table 2 andFig 1). There was statistically no significant difference observed in mean SNF percentage of cows fed with RPC. In line with findings, many researchers reported that RPC supplementation have no significant effect on the contents of protein, lactose, SNF and ash, but their yields increased (p<0.05) significantly ( [16,4,21,1] . On contrary, Rahmani et al. (2014) [14] concluded that feeding TMR top dressed with 90g/day RPC to early lactating Holstein cows had significantly improved the SNF content of milk (8.87±0.05 per cent) when compared to the control (8.67±0.04 per cent). Pawar et al. (2015) [11] revealed that no significant difference in milk composition of crossbred lactating cows supplemented with RPC. Neelima et al. (2021) [8] reported that supplementation of rumen protected choline @ 20 g/animal in early lactating cows had significant improvement (p<0.05) in SNF content as compared to control fed along with rumen protected methionine.

Rumen protected choline supplementation significantly improved (p<0.05) fat percentage. For every additional 0.1% increase in fat content farmer fetches Rs.0.20 paise and 0.1% increase in SNF content, farmer will get Rs. 0.40 paise. From the present study, the milk producer had received additional Rs.0.24 paise per litre by feeding of rumen protected choline because of improved fat percentage (Table 3). The total return was comparatively lower due to difference in their milk yield. This may due to difference in stage of lactation and length of the research period. The current prevailing market price of RPC was higher. However, long-term feeding of RPC may reduce the cost of production and improves animal health.

Conclusion

Based on the present study findings, it can be concluded that supplementation of rumen-protected choline at the rate of 20 g/animal/day did not result in significant improvements in milk yield or SNF content in lactating crossbred dairy cows. However, it significantly enhanced the milk fat content, which can positively influence the milk price. Therefore, inclusion of rumen-protected choline in the diet is recommended as a strategy to improve milk fat percentage and economic returns for dairy farmers.

Acknowledgement

AcknowledgementThe authors gratefully acknowledge Kemin Industries South Asia Pvt. Ltd., Chennai, for supplying the rumen-protected choline used in this study.

References

1. Ambrosio FD, Campagnoli A, Susca F, Fusi E, Rebucci R, Agazzi A, et al. Effects of rumen-protected choline supplementation in periparturient dairy goats. Vet Res Commun. 2007;31(1):393-396.
2. Cooke RF, Silva Del Rio N, Caraviello DZ, Bertics SJ, Ramos MH, Grummer RR. Supplemental choline for prevention and alleviation of fatty liver in dairy cattle. J Dairy Sci. 2007;90:2413-2418.
3. Elek P, Newbold JR, Gaal T, Wagner L, Husveth F. Effects of rumen protected choline supplementation on milk production and choline supply of periparturient dairy cows. Anim Biosci. 2008;2:1595-1602.
4. Erdman RA, Sharma BK. Effect of dietary rumenprotected choline in lactating dairy cows. J Dairy Sci. 1991;74:1641-1647.
5. Guretzky NAJ, Carlson DB, Garrett JE, Drackley JK. Lipid metabolite profiles and milk production for Holstein and Jersey cows fed rumen protected choline during the periparturient period. J Dairy Sci. 2006;89:188-200.
6. Hartwell JR, Cecava MJ, Donkin SS. Impact of dietary rumen undegradable protein and rumen-protected choline on intake, peripartum liver triacylglyceride, plasma metabolites and milk production in transition dairy cows. J Dairy Sci. 2000;83:2907-2917.
7. Mohsen MK, Gaafar HMA, Khalafalla MM, Shitta AA, Yousif AM. Effect of rumen protected choline supplementation on digestibility, rumen activity and milk yield in lactating Friesian cows. Slovak J Anim Sci. 2011;44(1):13-20.
8. Neelima J, Sajith P, Ally K, Deepa A, Shibu S. Effect of supplementation of rumen protected choline and methionine on milk yield and composition of early lactating dairy cows. J Vet Anim Sci. 2021;52(2):142148.
9. Neill AR. The low availability of dietary choline for the nutrition of sheep. Biochem J. 1979;180:559-565.
10. NRC. Nutrient requirements for dairy cattle. 7th rev ed. Washington (DC): National Academy Press; 2001. p. 1381.
11. Pawar SP, Kewalramani N, Thakur SS, Kaur J. Effect of dietary rumen protected choline supplementation on milk choline content in crossbred cows. Indian J Anim Nutr. 2015;32(1):30-35.
12. Piepenbrink MS, Overton TR. Liver metabolism and production of cows fed increasing amounts of rumen protected choline during the periparturient period. J Dairy Sci. 2003;86:1722-1733.
13. Pinotti L, Baldi A, Savoini G, Dell'Orto V. Effects of rumen protected choline on lipid metabolism in periparturient high yielding dairy cows. Livest Prod Sci. 2001;70:176.
14. Rahamani M, Dehghan-Banadaky M, Kamalyan R. Effects of feeding rumen protected choline and vitamin E on milk yield, milk composition, dry matter intake, body condition score and body weight in early lactating dairy cows. Iran J Appl Anim Sci. 2014;4(4):693-698.
15. Sharma BK, Erdman RA. in vitro degradation of choline from selected feedstuffs and choline supplements. J Dairy Sci. 1989;72:2772-2776.
16. Sharma BK, Erdman RA. Abomasal infusion of choline and methionine with or without 2-amino-2-methyl-1propanol for lactating dairy cows. J Dairy Sci. 1988;71:2406-2411.
17. Snedecor GW, Cochran WG. Statistical methods. 8th ed. Ames (IA): Iowa State University Press; 1994. p. 1503.
18. Suksombat W, Homkao J, Klangnork P. Effect of biotin and rumen protected choline supplementation on milk production, milk composition, live weight change and blood parameters in lactating dairy cows. J Anim Vet Adv. 2012;10:2186-2192.
19. Swartz TH, Bradford BJ, Malysheva O, Caudill MA, Mamedova LK, Estes KA, et al. Effects of dietary rumen-protected choline supplementation on colostrum yields, quality, and choline metabolites from dairy cattle. JDS Commun. 2022;3:1-8.
20. Xu G, Ye JA, Liu J, Yu Y. Effect of rumen protected choline addition on milk performance and blood metabolic parameters in transition dairy cows. AsianAustralas J Anim Sci. 2006;19(3):390-395.
21. Zahra LC, Duffield TF, Leslie KE, Overton TR, Putnam D, Leblanc SJ, et al. Effects of rumen protected choline and monensin on milk production and metabolism of periparturient dairy cows. J Dairy Sci. 2006;89:4808-4818.