Performance and blood parameters of Holstein / Zebu crossbred heifers fed with two tannins sources

The present research objective was to evaluate the performance and blood parameters of lactating cows fed with a diet of two tannin sources, based on sorghum (condensed tannin) Research, Society and Development, v. 9, n. 2, e128922150, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i2.2150 3 with increasing concentrations of tannic acid (hydrolyzable tannin’s). Increasing levels of tannic acid in a sorghum-based diet for five Holstein/Zebu crossbred lactating cows were subject to a 5 × 5 Latin square experimental design. To assess the effect on cow intake, digestibility, milk production, and blood parameters. All cows received 9.87 kg/DM of corn silage as roughage and 6.38 kg of concentrate consisting of 2.58 kg/DM of ground sorghum 0.87 kg/DM of cornmeal 1.32 kg/DM of soybean bran 0.44 kg/DM of wheat bran 0.2 kg/ DM of urea and 0.18 kg/ DM of mineral mixture. Diet 1 (control) contained low-tannin sorghum and the other diets contained high-tannin sorghum. The levels of tannic acid added to the diets were established based on the quantity of condensed tannin in high-tannin sorghum. Thus, diets 2, 3, 4 and 5 were supplemented with 1.5g (13.%DM), 79.5g (2.6%DM), 157.5g (3.9%DM) and 235.5g (5.2%DM) of tannic acid, totalling 0.078, 0.156, 0.234 and 0.321 total tannin kg/day respectively, to assess the effect on microbial protein synthesis. The diets contained 35 kg of corn silage (roughage) and 6.40 kg of concentrate. The natural and dry matter intake did not significantly differ between groups, except for ether extract (EE) intake that significantly differed. The DM apparent digestibility, crude protein, EE, neutral detergent fiber, total carbohydrate, and non-fibrous carbohydrate did not differ (P > 0.05) with the increase in dietary tannin supplementation. The GOT levels increased linearly. The blood glucose, triglyceride, and cholesterol (total, LDL and HDL) levels did not significantly differ. Hemoglobin showed a significant difference. No significant difference in urea, creatinine and uric acid occurred. Diets using two tannins sources supplementation caused no decrease in the dietary intake or digestibility in the animals. The GOT level changed significantly, showing linear behavior, however below the toxicity level, without any change in the other blood parameters. Milk production decreased with the increase in dietary tannin supplementation.

with 3.5% Ivermectin. The adaptation period to the facilities, the experimental diets and the stabling totalled 10 d.
The experimental diet consisted as roughage and concentrate, at fixed roughage: concentrate ratio of 64:36 as a TMR. The diet was offered in equal amounts twice a day at 06.00 AM and 01.30 PM after milking. Every day, orts from each animal were removed and weighed to calculate the food (natural and dry matter) intake. To ensure ad libitum access to the roughage, voluntary forage intake was determined daily, and roughage was fed at 140% of the average intake for the previous 5 d. The corn silage was produced at the Agricultural Science Centre/Federal University of Paraiba, Areia/PB.

Treatments
The experimental diet was formulated to meet the lactating demands according to recommendations from the NRC (National Research Council -NRC, 2001).
Diet 1 (control diet) contained BRS Ponta Negra cultivar sorghum (0.92% total condensed tannin in the DM) to provide the lowest possible amount of tannins. Diets 2, 3, and 4 contained A9904 cultivar sorghum (2.55% total condensed tannin in the DM), to provide the highest quantity of available tannins possible, in order to guarantee the tannin effects in animal metabolism.
The tannic acid levels added to the diets were established based on the analysis of the condensed tannin quantity in high-tannin sorghum. The levels of total condensed tannin (DM) in A9904 were calculated according to the HCl-butanol method (Hagerman & Butler, 1978) and the total condensed tannin in the DM in the control sorghum (BRS Ponta Negra cultivar) according to Terril et al. (1992) method, because of the different tannin content in each one.  Research, Society and Development, v. 9, n. 2, e128922150, 2020 (CC BY 4.   Tannic acid (C76H52O46) P.A. purchased from Anidrol® laboratory products, Sao Paulo-Brazil, a purified powder product was added to prepare the increasing tannin doses.
Predetermined proportions of powder tannic acid (based on the quantity of condensed tannin from sorghum A9904, 1.27, we've added, continuously, this same quantity, therefore, 2.6, 3.9, and 5.2, to find the final total percentages) were mixed with the concentrate on the day before trough feeding. Thus, diets 2, 3, 4 and 5 were supplemented with 1.5, 79.5, 157.5 and 235.5 g of tannic acid respectively, and provided an increase in the dietary total tannin percentages as outlined in Table 2. The DM, NDF and CP intakes as a function of live weight did not differ, possibly because the intake in absolute terms was not significantly affected, with initial body weight of 420 ± 30 kg and final BW 450 ± 35 kg. Thereby no decrease in intake occurred.
Sorghum is a widely produced cereal in the world, it's an excellent energy source for animal nutrition. It is found in its composition, phenolic compounds such as tannin, which is the most profuse compound in plants after cellulose, hemicellulose and lignin, it is soluble in water, acetone and alcohol. In plants, they may be found as condensed tannins or hydrolysable tannins. The simplest form of hydrolysable tannin, the tannic acid, can be degraded by the ruminal microorganisms. Makkar et al. (1995) reported that the presence of tannins in sorghum grain was associated with a low intake of DM, which was not observed in this experiment. Tannins form complexes with salivary glycoproteins (Goel et al. 2005 Research, Society and Development, v. 9, n. 2, e128922150, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i2.2150

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The DM, NDF and CP intakes as a function of live weight did not differ (P ≤ 0.05).
The average body live weight, feed efficiency, milk protein percentage and 4% fat-corrected milk production did not differ (P ≤ 0.05) with the increase in dietary tannins, as outlined in Table 4. Table 4-Mean body weight, feed efficiency, milk production, fat (%), protein (%) and 4% fatcorrected milk production of cows fed sorghum and increasing concentrations of tannic acid.

Ruminal digestibility
The apparent digestibility of DM, OM, CP, EE, NDF, TCH and NFC did not differ (P ≤ 0.05) regardless the dietary tannin, as outlined in Table 5. The maximum tannin dose provided (321 g) had no effect on the dietary nutrients digestibility. (AST)) levels showed significant differences (P ≤ 0.05) among the blood parameters tested (Table 6). adaptation to nutritional and physiological challenges and specific or nutritional metabolic imbalances (González & Scheffer 2002). These analyses enable the physiological changes assessment caused by dietary tannins in lactating cows. During the experiment time we didn't observe any change in blood parameters, which may indicate that no clinical damage was caused by tannins.
Total cholesterol remained high in all diets and LDL was low compared with HDL, which most likely indicated a weak liver fat effect. So, the milk fat may be primarily derived from acetates produced in the rumen.
The main hemoglobin function is oxygen transportation from the lungs to the body.
Hemoglobin is present in red blood cells, and it helps to some extent with nutrient transport to cells and collects toxic substances, including carbon dioxide, for subsequent release from the organism. Hemoglobin analysis is used to identify diseases such as anemia. According to Kaneko et al. (1997), the normal hemoglobin levels of cows range from 9 to 15 mg/dL; thus, the differences in hemoglobin levels found between treatments were within the normal range for cows.
In this experiment, at the highest dietary dose of tannic acid (235.5 g/day), 560 mg of tannic acid per kg/LW was provided to the cow with the lowest weight (± 420 kg). GOT and GPT (glutamate pyruvate transaminases or alanine transaminase (ALT)) are enzymes present in the liver and other organs, which, at high levels, indicate liver diseases. The GOT levels increased linearly (P ≤ 0.05). Despite this performance, the GOT levels at the highest dose of tannic acid were 84.59 U/L, which was still within the normal blood GOT levels for cows according to Kaneko et al. (1997), which range up to 132 U/L.

Conclusion
Diets using two tannins (hydrolysable and condensed) sources supplementation didn't decrease the dietary intake or affect the animals digestibility.
The GOT level changed significantly, showing linear behaviour, however below the toxicity level, with no change in the other blood parameters.
Milk production decreased with the increase in dietary tannin supplementation.
We recommend more studies using two tannin sources.