Polyhalite is a natural mineral that could be fed as an acidogenic product to induce a metabolic acidosis and prevent clinical hypocalcemia in dairy cows after calving. The overall objective of this study was to determine if the use of polyhalite mineral in the diets of pre-partum non-lactating dairy cows was effective as an acidogenic product. We measured the urine pH, dry matter intake, milk yield, and calcium and magnesium concentration of urine and serum in pre-partum and non-lactating dairy cows consuming diets containing a low dose of polyhalite (200 g/cow/day), a high dose of polyhalite (400 g/cow/day), calcium chloride (250 g/cow/day), or no acidogenic product. We hypothesized that including polyhalite mineral as an acidogenic product in the diets of pre-partum and non-lactating dairy cows will reduce urine pH and stimulate calcium metabolism mechanisms. We found that polyhalite effectively reduced urine pH and did not affect dry matter intake, and the stimulation of calcium metabolism was observed through an increase of calcium output in urine. In conclusion, feeding polyhalite mineral is an effective means for inducing metabolic acidosis without reducing dry matter intake. Based on these results, polyhalite should be fed at a dose of 400 g or more per cow per day to reduce urine pH. / Master of Science in Life Sciences / Low blood calcium concentration, also known as hypocalcemia, is one of the common metabolic disorders that affect dairy cows transitioning from the pre-partum to post-partum period. Reducing the dietary cation anion difference (DCAD) in cows during the close-up period is known to effectively reduce the probability of cows developing hypocalcemia after calving. Polyhalite is a natural mineral that could be fed as an acidogenic product to induce a metabolic acidosis and prevent hypocalcemia in dairy cows after calving. The overall objective of this study was to determine if the use of polyhalite mineral in the diets of pre-partum and non-lactating dairy cows was effective as an acidogenic product. We evaluated the urine pH, dry matter intake, milk yield, and calcium and magnesium concentration of urine and serum in pre-partum and non-lactating dairy cows consuming diets containing a low dose of polyhalite (200 g/cow/day) , a high dose of polyhalite (400 g/cow/day), calcium chloride (250 g/cow/day), or no acidogenic product. We hypothesized that including polyhalite mineral as an acidogenic product in the diets of pre-partum and non-lactating dairy cows will reduce urine pH and stimulate calcium metabolism mechanisms. We found that polyhalite effectively reduced urine pH and did not affect dry matter intake, and the stimulation of calcium metabolism was observed through an increase of calcium output in urine. In conclusion, feeding polyhalite mineral is an effective means for inducing metabolic acidosis without reducing dry matter intake. Based on these results, polyhalite should be fed at a dose of 400 g or more per cow per day to reduce urine pH.

The study objectives were to determine the dry matter intake, urine pH, Ca concentration in blood, Ca output in urine, and incidence of hypocalcemia from pregnant, non-lactating dairy cows during the prepartum period consuming diets containing either grass hay (GH) or alfalfa hay (AH) with the inclusion of either calcium chloride (CL) or polyhalite mineral (PO). Eighty Holstein cows in their 2nd parity or greater were fed an experimental diet according to a 2 2 factorial arrangement of treatments during the prepartum period (21 d before calving). All diets had a dietary cation-anion difference (DCAD) below -190 mEq/kg/DM. Grass hay contained 7.5% CP, 74.9% NDF, 0.36% Ca, 0.02% Na, 1.88% K, 0.38% Cl, and 0.15% S. Alfalfa hay contained 19.6% CP, 45.6% NDF, 1.52% Ca, 0.16% Na, 2.5% K, 0.77% Cl, and 0.32% S. Cows consuming grass hay tended to consume more dry matter than cows consuming alfalfa hay (11.6 vs 10.8 kg/d), but dry matter intake (DMI) was not affected by the acidogenic products. Urine pH decreased below 6.5 for all diets and was greatest for cows consuming the GHPO diet. The concentration of calcium in plasma decreased significantly (P < 0.01) around calving but neither the hay type (P=0.86) nor the acidogenic product (P =0.81) affected it. Urinary calcium output was less for cows consuming the GHPO diet. Cows consuming diets containing alfalfa hay had a greater incidence of normocalcemia (37 and 40% for AHCL and AHPO, respectively) than cows consuming diets containing grass hay (20 and 25% for GHCL and GHPO, respectively). In conclusion, alfalfa hay can be included in prepartum diets without necessarily increasing the incidence of hypocalcemia, and the cation-anion difference of alfalfa hay is a determinant of whether it can be included in the prepartum diet. / Master of Science in Life Sciences / Hypocalcemia, low concentrations of calcium in the blood, is more prevalent during the transition from pregnancy to post-pregnancy and can be diagnosed through blood analysis or by observing physical symptoms. The dietary cation-anion difference (DCAD) is the acid-base regulation of the diet and has been used to prevent hypocalcemia during the pre-calving period. The objective of this study was to feed 2 types of hay and 2 types of acidogenic products (Grass Hay/Calcium Chloride, Grass Hay/POlyhalite, Alfalfa Hay/Calcium Chloride, and Alfalfa Hay/POlyhalite) to non-lactating cows in their pre-calving period and observe variables in relation to the incidence of periparturient hypocalcemia. The variables included plasma and urine calcium concentrations pre-calving (21 days) and post-calving (3 days), dry matter intake (DMI) during the pre-calving period, and urine pH. Cows decreased in their dry matter intake toward calving and consumed more grass hay than alfalfa hay (11.6 vs. 10.8 kg/d). All four diets were in a negative DCAD and successfully decreased urine pH for all cows. Calcium concentrations in plasma decreased around calving, but this was not affected by hay type or acidogenic product. Urinary calcium output was greatest in the GHCL-fed cows. The study resulted in further differentiation of cows with plasma calcium concentrations ≤ 5.5 mg/dL without physical symptoms and an animal with ≤ 5.5 mg/dL and a loss of muscle function. Only one cow had a loss of muscle function; however, 13 out of 79 cows had calcium concentrations that according to past research, should've resulted in this. Additionally, 44 out of 79 cows had calcium concentrations between 5.5 and 8.0 mg/dL at least once after calving. In conclusion, alfalfa can be included in pre-calving diets as long as the DCAD is negative.

Diet and exercise are two manageable factors that affect bone remodeling. Experiments were designed to test the hypothesis that bone density and calcium status would be affected by conditioning and deconditioning, and by dietary Ca and cationanion difference (DCAD). In experiment one, 12 Arabian horses were conditioned for 12 wk on a high speed equine treadmill. Diets were designated LH, which contained low Ca (.35%)-high Cl (.6%), LL, low Ca-low Cl (no added Cl), HH, high Ca (.7%)- high Cl, and HL, high Ca-low Cl. Data were collected while horses were at rest every 21 d. Serum and plasma were analyzed for total and ionized Ca, P, Mg, Cl, total protein, albumin, parathyroid hormone (PTH), osteocalcin, and hydroxyproline. Radiographs of the left third metacarpal bone were taken. An aluminum step wedge exposed simultaneously was used as a reference standard for estimating bone mineral content (BMC) with an image analysis program. Bone measurements, including BMC, bone and medullary width, and cortical area, were taken in the proximal diaphyseal and proximal metaphyseal area. Bone variables increased with training and with high Ca diets as compared to horses fed low Ca diets. Serum Ca decreased and serum PTH increased with training. Hydroxyproline was unchanged in horses fed the low Ca diets and decreased in horses fed the high Ca diets. Serum osteocalcin increased then decreased with training. The high Ca diet appeared to facilitate bone remodeling in response to training, but dietary Cl, hence DCAD, had no effect. In experiment two, 11 conditioned Arabian horses were taken out of training and placed in stalls for 12 wk. They were walked on a mechanical walker in two 30 min sessions 7 d/wk. Diets were designated LC (.35% Ca) and HC (.7% Ca). Data collection and analysis were identical to those in experiment one. Bone variables decreased with deconditioning but were unaffected by dietary Ca. Serum Ca increased with deconditioning and was greater in horses fed the HC diet, but PTH did not change. Horses fed the HC diet had greater serum osteocalcin, which decreased with deconditioning. Dietary Ca influenced bone remodeling in response to training, but did not have an effect on bone response to deconditioning. Loss of BMC during 12 wk of stall confinement may predispose horses to skeletal injuries when training is resumed. / Ph. D.

In this work, there was observed the influence of feeding an anionic salt on acid-base value in the urine (ABV) and on a level of the calcium in the urine in high yielding dairy cows. This mineral ingredient was tested for two feeding rates: winter - conserved, summer - pasture and was fed in a rate 450 g per a cow and a day. In the winter experimental period there were found no changes in AVB and the effect of Rindavit MF Sauer wasn´t expressed. In the sum-mer experimental period the influence of Rindavit MF Sauer on acid-base balance was fully expressed although the high potassium level in the feed rate. We found statistically significant differences between control and experimental group at observing levels of calcium and the effect of the anionic salt was shown. There was found no case of the milk fever in experimental group cows dduring the whole test. By contrast, there were recorded two cases of the milk fever in the control group cows. At feeding the anionic salt, we didn't find any negative effect on the acid - base balance and the health of the cows.

O presente estudo objetivou avaliar o efeito do balanço cátion-aniônico da dieta sobre: (a) concentração de subunidades de caseína, proteínas do soro, cálcio iônico e estabilidade do leite ao etanol e ao aquecimento a 140&ordm; C; (b) metabolismo digestivo, renal e sanguíneo de vacas leiteiras em lactação. Foram utilizadas 16 vacas da raça Holandês, com 158 &plusmn; 52 dias em lactação, distribuídas em 4 quadrados contemporâneos em um delineamento Quadrado Latino 4 x 4, com 4 períodos de 21 dias e 4 tratamentos. Os tratamentos experimentais consistiram de 4 níveis de balanço cátion-aniônico da dieta (BCAD): +290; +192; +98 e -71 mEq/kg de MS. No presente estudo, o consumo de matéria seca, as concentração de ácidos graxos de cadeia curta (AGCC) e o pH do fluído ruminal, e a digestibilidade aparente total da FDN aumentaram de acordo com o aumento do BCAD. De forma semelhante, a produção de leite corrigida para gordura, e os teores de gordura, lactose, e sólidos totais do leite aumentaram linearmente em 13,52, 8,78, 2,5 e 2,6%, respectivamente, quando o BCAD aumentou de -71 para 290 mEq/kg MS; enquanto que os teores de proteína bruta e de caseína reduziram linearmente em 4,83 e 4,49%, respectivamente. Adicionalmente, a concentração sanguínea de HCO3&#x2D; o pH do sangue e a excreção urinária de Na e K aumentaram de acordo com o BCAD, o que reduziu as concentrações sanguíneas de cátions (Na, K e Ca iônico) e, consequentemente, a concentração de Ca iônico do leite. Como resultado da redução da concentração de Ca iônico, a estabilidade do leite ao etanol e ao aquecimento a 140&ordm; C aumentaram linearmente com o BCAD [&#x59; = 74,87 (EP = 0,87) + 0,01174 (EP = 0,0025) × BCAD (mEq/kg MS) e &#x59; = 3,95 (EP = 1,02) + 0,01234 (EP = 0,0032) × BCAD (mEq/kg MS), respectivamente]. Desta forma, pode-se concluir que o BCAD aumenta o desempenho produtivo de vacas leiteiras em lactação e, adicionalmente, eleva a capacidade relativa das proteínas do leite em resistir à coagulação ao teste do álcool e durante o aquecimento do leite a 140&ordm; C. / The present study aimed to evaluate the effect of dietary cation-anion difference (DCAD) on: (a) concentrations of casein subunits, whey proteins, ionic calcium, and milk ethanol and heat stability at 140&ordm; C; (b) digestive, renal and blood metabolism of dairy cows. Sixteen Holstein cows, with 158 &plusmn; 52 days in milk, were distributed in 4 contemporary 4 x 4 Latin Square design, with four periods of 21 days and 4 treatments. The experimental treatments consisted in 4 levels of dietary cation-anion difference (DCAD): +290; +192; +98 e -71 mEq/kg DM. In the present study, dry matter intake, the concentration of short chain fat acids (SCFA) and ruminal pH, and the NDF total apparent digestibility increased according to DCAD increases. Similarly, fat-corrected milk and fat, lactose and total milk solids content were linearly increased by 13.52, 8.78, 2.5 and 2.6%, respectively, according to DCAD increases from -71 to 290 mEq/kg DM; while crude protein and casein content were linearly reduced by 4.83 and 4.49%, respectively. In addition, blood concentration of HCO3&#x2D;, o pH of blood, and urinary excretion of Na and K increased according to DCAD, which reduced the blood concentrations of cations (Na, K and ionic Ca) and, consequently, the milk concentrations of ionic Ca. As a result of reduction of ionic Ca concentration, the milk ethanol and heat stability at 140&ordm; C linearly increased with DCAD [&#x59; = 74.87 (SE = 0.87) + 0.01174 (SE = 0.0025) × DCAD (mEq/kg DM) and &#x59; = 3.95 (SE = 1.02) + 0.01234 (SE = 0.0032) × DCAD (mEq/Kg DM), respectively]. Thus, it may be concluded that DCAD increases the productive performance of lactating dairy cows and, additionally, increases the relative capacity of milk proteins to resist the coagulation at alcohol test and during heat treatment at 140&ordm; C.

O presente estudo objetivou avaliar o efeito do balanço cátion-aniônico da dieta sobre: (a) concentração de subunidades de caseína, proteínas do soro, cálcio iônico e estabilidade do leite ao etanol e ao aquecimento a 140&ordm; C; (b) metabolismo digestivo, renal e sanguíneo de vacas leiteiras em lactação. Foram utilizadas 16 vacas da raça Holandês, com 158 &plusmn; 52 dias em lactação, distribuídas em 4 quadrados contemporâneos em um delineamento Quadrado Latino 4 x 4, com 4 períodos de 21 dias e 4 tratamentos. Os tratamentos experimentais consistiram de 4 níveis de balanço cátion-aniônico da dieta (BCAD): +290; +192; +98 e -71 mEq/kg de MS. No presente estudo, o consumo de matéria seca, as concentração de ácidos graxos de cadeia curta (AGCC) e o pH do fluído ruminal, e a digestibilidade aparente total da FDN aumentaram de acordo com o aumento do BCAD. De forma semelhante, a produção de leite corrigida para gordura, e os teores de gordura, lactose, e sólidos totais do leite aumentaram linearmente em 13,52, 8,78, 2,5 e 2,6%, respectivamente, quando o BCAD aumentou de -71 para 290 mEq/kg MS; enquanto que os teores de proteína bruta e de caseína reduziram linearmente em 4,83 e 4,49%, respectivamente. Adicionalmente, a concentração sanguínea de HCO3&#x2D; o pH do sangue e a excreção urinária de Na e K aumentaram de acordo com o BCAD, o que reduziu as concentrações sanguíneas de cátions (Na, K e Ca iônico) e, consequentemente, a concentração de Ca iônico do leite. Como resultado da redução da concentração de Ca iônico, a estabilidade do leite ao etanol e ao aquecimento a 140&ordm; C aumentaram linearmente com o BCAD [&#x59; = 74,87 (EP = 0,87) + 0,01174 (EP = 0,0025) × BCAD (mEq/kg MS) e &#x59; = 3,95 (EP = 1,02) + 0,01234 (EP = 0,0032) × BCAD (mEq/kg MS), respectivamente]. Desta forma, pode-se concluir que o BCAD aumenta o desempenho produtivo de vacas leiteiras em lactação e, adicionalmente, eleva a capacidade relativa das proteínas do leite em resistir à coagulação ao teste do álcool e durante o aquecimento do leite a 140&ordm; C. / The present study aimed to evaluate the effect of dietary cation-anion difference (DCAD) on: (a) concentrations of casein subunits, whey proteins, ionic calcium, and milk ethanol and heat stability at 140&ordm; C; (b) digestive, renal and blood metabolism of dairy cows. Sixteen Holstein cows, with 158 &plusmn; 52 days in milk, were distributed in 4 contemporary 4 x 4 Latin Square design, with four periods of 21 days and 4 treatments. The experimental treatments consisted in 4 levels of dietary cation-anion difference (DCAD): +290; +192; +98 e -71 mEq/kg DM. In the present study, dry matter intake, the concentration of short chain fat acids (SCFA) and ruminal pH, and the NDF total apparent digestibility increased according to DCAD increases. Similarly, fat-corrected milk and fat, lactose and total milk solids content were linearly increased by 13.52, 8.78, 2.5 and 2.6%, respectively, according to DCAD increases from -71 to 290 mEq/kg DM; while crude protein and casein content were linearly reduced by 4.83 and 4.49%, respectively. In addition, blood concentration of HCO3&#x2D;, o pH of blood, and urinary excretion of Na and K increased according to DCAD, which reduced the blood concentrations of cations (Na, K and ionic Ca) and, consequently, the milk concentrations of ionic Ca. As a result of reduction of ionic Ca concentration, the milk ethanol and heat stability at 140&ordm; C linearly increased with DCAD [&#x59; = 74.87 (SE = 0.87) + 0.01174 (SE = 0.0025) × DCAD (mEq/kg DM) and &#x59; = 3.95 (SE = 1.02) + 0.01234 (SE = 0.0032) × DCAD (mEq/Kg DM), respectively]. Thus, it may be concluded that DCAD increases the productive performance of lactating dairy cows and, additionally, increases the relative capacity of milk proteins to resist the coagulation at alcohol test and during heat treatment at 140&ordm; C.