Acid-base variables during incremental exercise in sprint-trained horses fed a high-fat diet

Abstract

Seven Arabian horses performed a standard incremental exercise test on a high-speed treadmill at 6% slope then were randomly assigned to two diets, a control diet of ground hay and concentrates and a similar diet with 10% added fat (by weight). Horses were sprint-trained 4 d/wk, and two additional exercise tests were performed at 5-wk intervals. Heart rates and rectal temperatures were monitored and venous blood samples were collected at rest and at each speed increment. Whole blood was analyzed for glucose, lactate, and hemoglobin concentrations, and plasma was analyzed for pH, pCO2, albumin, total protein, and sodium, potassium, and chloride concentrations. Bicarbonate concentration ([HCO3-]) and strong ion difference ([SID]) were calculated, and total weak acid ([Atot]) was estimated from total protein. During exercise, there were increases in plasma sodium and potassium concentrations (P < .001), whole blood lactate and glucose (P < .001), and hemoglobin concentrations (P < .01). There were decreases in plasma pH, [HCO3-], and chloride concentrations (P < .001). The decrease in plasma pH was associated with changes in [SID] and [Atot] that combined to offset a decrease in pCO2. After sprint training, heart rates at rest and during submaximal exercise were decreased (P < .01), whereas heart rates at the end of exercise were increased (P < .05). Sprint training also increased workrate and estimated oxygen consumption at a heart rate of 200 beats/min (P < .001). Training increased the duration of exercise and the speed attained at the end of exercise (P < .05). Training increased the blood hemoglobin response to exercise and decreased the pCO2 response (P < .01). There were diet x training interactions for pH, pCO2, and [SID] (P < .05). Horses consuming the high-fat diet had higher blood glucose during both standard exercise tests and higher lactate concentrations at fatigue (P < .05) during the last test. Fat adaptation involving sprint training of horses may influence glucolysis at the level of pyruvate during an incremental exercise test.

Uso de óleo na dieta de eqüinos submetidos ao exercício

“…Taylor et al (1995) e Frape (1994 constataram níveis mais elevados de glicose, enquanto Scott et al (1992) e Marqueze et al (2001) não observaram alterações nos níveis de glicose em cavalos exercitados a intensidades alta e média, respectivamente. Meyer et al (1989) encontraram menores teores de glicose em cavalos submetidos a exercício-teste alimentados com dieta contendo 10% de gordura em comparação à dieta sem óleo.…”

“…De acordo com pesquisas, cavalos treinados e adaptados a dietas suplementadas (de 21 dias a 8 meses) com gordura aumentam o metabolismo lipídico, ou seja, apresentam maior capacidade de oxidar ácidos graxos para utilizá-los como fonte de energia, poupando as reservas de glicogênio (Jones et al, 1992;Meyer et al, 1989;Oldham et al, 1990;Scott et al, 1992;Harkins et al, 1992). Ao mesmo tempo, tem-se verificado aumento na concentração de lactato após o exercício em cavalos alimentados com dietas contendo gordura (Ferrante et al, 1994;Taylor et al, 1995;Oldham et al, 1990). Segundo Taylor et al (1995), o aumento na oxidação de ácidos graxos eleva a produção de acetil-CoA, inibindo a enzima piruvato desidrogenase e, com isso, aumenta a concentração de piruvato.…”

“…Ao mesmo tempo, tem-se verificado aumento na concentração de lactato após o exercício em cavalos alimentados com dietas contendo gordura (Ferrante et al, 1994;Taylor et al, 1995;Oldham et al, 1990). Segundo Taylor et al (1995), o aumento na oxidação de ácidos graxos eleva a produção de acetil-CoA, inibindo a enzima piruvato desidrogenase e, com isso, aumenta a concentração de piruvato. Este piruvato "sobressalente" é convertido em lactato em condições de deficiência de oxigênio.…”

Efeito da suplementação com concentrados ricos em óleo sobre biomarcadores metabólicos para cavalos

“…Diferentes pesquisa têm demonstrado que a inclusão de óleo em rações para cavalos podem não provocar modificações no perfil hematimétrico dos animais por favorecer a estabilidade da parede celular (Hambleton et al, 1980;Taylor et al, 1995). Recentemente, Mélo et al (2012) relataram que a suplementação de potros apartados com concentrados rico em óleo (20% de EE) não foi capaz de modificar os parâmetros associados aos glóbulos vermelhos, no entanto, produziu redução na contagem de glóbulos brancos após 60 dias de suplementação.…”

Acid-base balance parameters and a value of anion gap of arterial and venous blood in Małopolski horses

“…In the veterinary medicine, the ABB parameters are used mainly in sport horses for the assessment of the impact of training on the oxygen content and the carbon dioxide content in the arterial and venous blood (Nolte et al 1982, Greene et al 1991, Aguilera-Tejero et al 2000, Fenger et al 2000, Bayly et al 2006) and the impact of high-fat and high-protein feed on maintaining proper blood pH in the course of training (Ferrante et al 1994, Taylor et al 1995, Zeyner et al 2002, Connysson et al 2006. In sport horses, the ABB should be regularly checked during a sodium bicarbonate therapy.…”