Finding the impact of WB 02 straw based diet on milk composition of Murrah Buffaloes

Introduction

India has 109.85 million buffaloes with overall milk production of 221.06 million tonnes. In India, buffaloes are given more preference than cattle as the former can be maintained on feed and fodders having low nutritional values, provide higher milk fat yield (more than 8%), and thus better feed conversion efficiency, which ultimately results in a higher economic return (Balhara et al., 2017) [1] . ICAR-IIWBR, Karnal, Haryana, developed a biofortified wheat variety that was released in 2017 by the Government of India. This variety, known as WB-02, is a pure line cultivar with a rich content of zinc and iron in the grains, i.e., 42.0 and 40.0 ppm, respectively (Yadava et al., 2018) [14] . A higher zinc level and improved dry matter digestibility in vitro were the outcomes of this biofortification. Zinc and iron concentrations in grains and straw rice increase whenever foliar application is done (Paramesh et al., 2020) [8] . Increased availability of zinc to dairy animals via zinc-enriched fodder might help meet the requirement (Capstaff and Miller, 2018) [2] . Cow milk usually contains 3-5 mg Zn/l, predominantly associated with casein (Goff and Stabel, 1990) [5] . Additionally, Trávníček et al. (2004) [12] reported that there is a correlative dependency between the Zn content and the level of milk proteins in raw cow milk (rxy = 0.30). Keeping the above facts in mind, the present study was conducted to study the effect of feeding a biofortified wheat (WB-02) straw-based diet on the milk composition of lactating Murrah buffaloes (Bubalus bubalis).

Materials and Methods

Twelve recently calved Murrah buffaloes, sourced from the Livestock Research Center, ICAR-NDRI, Karnal, were divided into two groups based on body weight, production capacity, and lactation stage. The experiment adhered to Institutional Animal Ethics Committee (IAEC) guidelines under CPCSEA regulations. Before the feeding trial, all animals were dewormed. They were housed in well-ventilated tie-stalls with separate feeding arrangements. Both groups received a total mixed ration (TMR) in a 50:15:35 ratio (Wheat Straw: Green Fodder: Concentrate) based on dry matter (DM), following ICAR (2013) specifications. The control group was given conventional wheat straw, while the treatment group received WB 02 straw. Daily logs of feed and leftovers were maintained throughout the trial. At 10:00 a.m., precisely measured TMR, comprising wheat straw, concentrate mixture, and chaffed green fodder, was provided. Buffaloes had unrestricted access to poTable drinking water. The frequency of milk sampling was weekly, during the morning (0500 hours) and evening (1800 hours) milking. Determination of milk composition was done by collecting about 100 ml milk sample from individual animal of each milking at weekly interval in a properly cleaned milk sample bottle. The milk constituents such as fat, protein, lactose and SNF were analysed by Lacto Scan-automatic milk analyser. Statistical analysis was carried out using IBM SPSS (26.0) and ANOVA feature was used to compare the means at different intervals.

Results and Discussion

The price of milk in India is heavily influenced by the amount of fat in the milk. Additionally, for the production of valueadded dairy products, milk containing a higher fat content is tremendously demanded, prompting the livestock rearing community to strive for milk with an improved fat level. The data on milk fat percentage, recorded on a weekly basis, are presented in Table 1. These values were in the range of 5.42±0.13% to 6.62±0.36% and 5.53±0.37 to 6.58±0.51% for the control (T0) group and the treatment (T1) group, respectively. It was observed that both groups were statistically at par with each other (p>0.05). Limited literature is available for comparative study with respect to the effect of feed biofortified with zinc and iron on milk fat content. Nevertheless, Sobhanirad et al. (2010) [11] observed no significant improvement in cattle milk fat percentage following zinc supplementation. Furthermore, Weiss et al. (2010) [13] , in their study of supplementing organic iron to cattle, failed to report any effect on milk fat content. , reported no discernible effect on milk SNF levels following zinc supplementation in cattle. Similar results were also observed by Shafi et al. (2020) [9] , where zinc supplementation in goats failed to impact the milk SNF content. Moreover, there is a noTable absence of available studies demonstrating the effect of zinc and iron biofortified feed on milk SNF in comparison with the findings of the current study.

The data in Table 3 represents the mean values of milk protein percentage measured weekly. These values were in the range of 3.62±0.04% to 4.03±0.08% and 3.75±0.07% to 4.09±0.09% for the control (T0) group and the treatment (T1) group, respectively. It was observed that there was no statistically significant difference between the two groups with respect to milk protein level (p>0.05). These results were consistent with the studies conducted by Sobhanirad et al. (2010) [11] , where they reported no profound effect on milk protein following zinc supplementation in cattle. Similarly, Shafi et al. (2020) [9] also documented no significant effect on milk protein content when goats were provided with supplemental zinc. In contrast, Singh et al.

(2021) [10] observed an improvement in milk protein level upon zinc supplementation in Murrah buffaloes. Further, in an experiment conducted by Weiss et al. (2010) [13] , organic iron supplementation in cattle failed to improve protein content in milk. In a few studies conducted on cattle where they were fed a ration supplemented with zinc, the differences in milk lactose content were non-significant (p>0.05). (Sobhanirad et al., 2010) [11] . Shafi et al. (2020) [9] , in their study on goat milk, also found similar results. Moreover, there is not any published report available for the comparison that demonstrates feed biofortified with iron and zinc having an influence on milk lactose content.

Conclusion

In conclusion, the study focused on the impact of feeding biofortified wheat straw-based diets on the milk composition of lactating Murrah buffaloes. The introduction of WB-02 straw did not significantly alter the milk fat, solid not fat (SNF), protein, or lactose content when compared to the conventional straw. The study contributes valuable insights into the limited existing literature on the influence of zinc and iron biofortified feed on milk composition in buffaloes. Further research is warranted to explore potential correlations between biofortified feed and milk composition in different livestock species, thereby advancing our understanding of nutritional strategies for improved dairy production.

Authorship Contribution Statement

Davender Singh Kalwani carried out the experiment. Yash Parsana prepared the manuscript draft. Arun Kumar Misra designed the experiment and edited the draft.

Acknowledgement

AcknowledgementsAuthors duly acknowledge the support provided by the Director ICAR-National Dairy Research Institute for carrying out the above work. Authors would also like to thank ICAR-NIANP for the funding of the project.

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