Dairy Feed Resources and Mineral Assessment in Selected Districts of East Shoa Zone Effects of Dicalcium Phosphate Supplementation on Milk Yield and Composition in Crossbred Dairy Cows
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2020-06
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The present study conducted to assess dairy feed resources mineral composition and dairy cow blood mineral profiles in selected districts of East Shoa Zone, and assess the effects of dicalcium phosphate supplementation on milk yield and composition in Crossbred Dairy Cows. The whole work was conducted in two major parts with sub-activities in each part. The first activity of part one was surveyed to assess the socioeconomic status of dairy farmers and feed resources available with feeding patterns in the urban and peri-urban production system of Ada’a and Adama district. The second activity of part one was minerals profile assessment both from dairy feeds resources and from dairy cow serum at different physiological status. The assessment was performed in a wet and dry season of the year. Part two was on-station mineral supplementation experimental trial to investigate the effect of mineral supplementation on blood, feed, milk, urine and feces mineral profile, feed intake, milk yield and composition of crossbred dairy cows. For part one, the sampling frame comprises farmers keeping crossbred dairy cows and a total of 250 households were purposively selected. The study districts and the production systems (urban and peri-urban) were selected purposively based on the availability of dairy farms, having crossbreed dairy cows. A total of 240 blood samples (120 at dry and 120 at wet season) and 140 feed samples were collected from the dairy farms where blood was taken. Feed samples were categorized based on the production system and seasons and were dried and grounded. The grounded feed samples and serum were stored at -200C until to be analyzed. The serum and feed samples were analyzed for Calcium (Ca), Magnesium (Mg), phosphorus (P), Copper (Cu), Iron (Fe), zinc (Zn) and Cobalt (Co). The mean value of calcium ranges from (0.13 to 0.55 %); (0.14 to 0.64 %); (0.34 to 0.69 %) respectively, in roughage, Cereal grain & oilseed cakes and non-conventional. Out of the total feeds analyzed 26.92%, roughage (natural grass hay, sugar cane tops, and silage) and 66.15% cereal grain & oilseed cakes, showed deficiency in Ca. The mean magnesium and Iron values were not deficient in analyzed feeds. The mean Copper concentrations were ranges from in (6.99 to 10.65 ppm); (6.67 to 8.78 ppm); (6.31 to 9.72 ppm) respectively, roughages, Cereal grain & oilseed cakes and non-conventional. When the Cu concentration values are compared to the critical value (<8ppm) of feeds analyzed, 19.23%, 79.92% and 65.22% for roughage concentrate and non-conventional feeds respectively, were found to be deficient in Cu. The mean Iron concentrations varied in roughages (68.5 to 176.80 ppm); concentrate (73.94 to 174.81 ppm) and non-conventional (65.92 to 157.93 ppm) DM, respectively. When those values are compared to the critical value of (50 ppm) of feeds analyzed only 48.1% and 34.8% for roughage (natural pasture, Pennisetumpurpureum), sugar cane top) and non-conventional feeds (brewery by-products industrial), respectively, were found to be deficient in Zn. The interaction effect of dairy feeds, for most analyzed feed samples, were significantly different (P<0.05) for all Ca, P, Mg, Cu, Fe, and Zn within the study districts. Similarly, the interaction effect between feed types and production systems were significantly different (P<0.05) for Ca, P, Mg, Cu, and Zn. Moreover, the interaction
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effect of feed and sampling season was significantly different (P<0.05) for Ca, P, Mg, and Zn. Therefore, in this study minerals most widely present in inadequate amounts were Ca, P, Cu Zn and Co indifferent proportion based on seasons. Likewise, the overall mean blood serum concentration result was 0.080,0.082g/L for lactating and 0.090, 0.081g/L for dry dairy cows in the dry and wet season, respectively for Ada’a and Adama district. In lactating and dry cows, in both districts mean serum calcium concentration was very close to a critical level (CL) or close to borderline to develop clinical signs of hypocalcemia. The overall percentage of Ca deficiency based on the critical level (23.34, 29.32%); (23.34, 18.54%) for lactating cows and (7.12, 8.32%); (11.13, 6.34%) for dry cow were deficient in Ca in urban and peri-urban Ada’a and Adama districts, respectively. Likewise, seasonally Ca deficiency was (26.67, 21.67%); (31.67, 27.67%) for the dry season and (11.67, 26.67%); (34.67, 16.67%) wet season in urban and peri-urban Ada’a and Adama districts, respectively. Moreover, Ca in serum P, Cu, and Co were deficient from collected samples during the study period. Whereas, based on the mean value serum concentration of Mg, Zn, Fe was sufficient in the production system and season. Likewise, overall mean serum phosphorus was (0.037, 0.039 g/L) for lactating cows during dry and wet season whereas, (0.038, 0.037 g/L) for dry dairy cows in the dry and wet season, respectively. The difference in mean serum magnesium was significant (P<0.05) within the production system, the physiological state of dairy cows and seasons. Similarly, the difference in serum copper, Fe, and Zn level was statistically significant (p<0.05) based on the physiology of cows, production system and season. In Part II dicalcium phosphate-18% was supplemented for 120 days of feeding trial period classified into four periods which consists of 30 days each (16 days of adaptation and 14days of data collection) and at different levels (0, 0.3, 0.6, 0.9%) in lactating cows in their 1st- 4th lactation stage using 4X4 Latin square design. The effect of mineral supplementation was evaluated by taking blood, milk, urine, feces, feed refusals for laboratory analysis. Results of the present study revealed that supplementation of 0.3%, 0.6%, 0.9% dicalcium phosphate with the concentrate mix was improving dry matter intake, digestibility of nutrients in lactating dairy cows compared to the controls. However, increasing the level of supplementation affect milk production, and composition compared to non-supplemented groups except SNF. There was a significant difference (P < 0.05) between treatment groups in serum phosphorus. No difference between treatment groups was observed for serum calcium. Finally, from the current finding, it could be concluded.Ca, P, Cu, Zn, and Co was found deficient in dairy feed. Similarly, serum samples showed Ca, P, Cu, and Co to be below the critical level or close to lower borderline. While, the levels of Mg, Fe and Zn were sufficient to meet estimated nutritional requirements for dairy cows. The level of Co concentration was even not detected both on feed and blood samples, which indicate Co was below the critical level. The amount of minerals in analyzed feed significantly varies by study districts and season. Supplementation of 0.3% of 0.6%, 0.9% dicalcium phosphate with the concentrate mix was improving dry matter and nutrient intake. Supplementation of DCP-18% significantly increase milk production, and composition compared.Therefore, supplementation regimes of these mineral elements are very likely to improve production, and reproduction efficiency. However, research that covers a wider area and that asses the effect of other mineral supplementation should be conducted.
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Dairy cows, AAS, East Shoa Zone, DCP-18%, Feed, Serum mineral, Production system