Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram).

Individually caged male Cobb broilers (24), 44 d of age, were used to evaluate effects of heat stress (1 d of data collection) and dietary electrolyte balance (DEB; Na + K - Cl, mEq/kg from 1 d of age). During summer rearing, mortality was variable, but DEB 240 improved growth, feed conversion ratio, water intake, and water:feed ratio vs. DEB 0. The temperature sequence for heat stress was 24 to 32 degrees C in 30 min, 32 to 36 degrees C in 30 min, 36 to 37 degrees C in 15 min, and 37 to 41 degrees C in 45 min. Maximum temperature was held for 15, 60, 90, or 360 min for data collection (relative humidity averaged 42 +/- 7%). Results from the same room before and after heat stress were analyzed by DEB (1-factor ANOVA) and before vs. after heat stress compared across DEB (2-sample t-test). Heat stress decreased blood Na, K, and pCO2, and lymphocytes but increased heterophils. Blood HCO3 rose, Cl declined, and hematocrit gave a concave pattern (lowest at DEB 120) as DEB increased. After heat stress, DEB 0 decreased blood Na and K, and DEB 0 and 120 levels decreased blood HCO3. After heat stress blood pCO2 and hemoglobin decreased with DEB 240, but it had highest pCO2, a key factor. The DEB 120 gave longest times to panting and prostration with DEB 0 and 240 results lower but similar statistically. In heat stress, DEB 360 was excessive, DEB 120 and 240 were favorable, and DEB 0 was intermediate based on hematology, panting, and prostration responses.

Dietary electrolyte balance for broiler chickens exposed to thermoneutral or heat-stress environments.

Ross male broiler chicks (n = 480) on new litter were used in a randomized block design with two blocks (environmental rooms) and four treatments having four replicate pens (1.0 x 2.5 m; 15 chicks) each to evaluate dietary electrolyte balance (DEB; P < 0.05). Two rooms were 1) thermoneutral (Weeks 1 through 6, with decreasing maximum from 32 to 25 degrees C and minimum from 28 to 19 degrees C; relative humidity 49 to 58%) and 2) cyclic daily heat stress (Weeks 1 and 2, thermoneutral; Weeks 2 through 6, maximum temperatures 35, 35, 33, and 33 degrees C, respectively; and minimum temperatures 23, 20, 19, and 19 degrees C, respectively; relative humidity 51 to 54%). The DEB treatments (0, 140, 240, or 340 mEq Na + K - Cl/kg) had NaHCO3 plus NH4Cl, or KHCO3, or both added to corn-soybean meal mash basal diets with 0.30% salt (NaCl). In the thermoneutral room, DEB 240 increased 42-d weight gain and 44-d lymphocyte percentage and decreased heterophil percentage and heterophil to lymphocyte ratio compared to the DEB 40 treatment. The DEB 240 diets had 0.35 and 0.35% Na and 0.37% and 0.29% Cl in starter (0.75% K) and grower (0.67% K) diets, respectively. No DEB treatment differences were found in the heat stress room. For combined rooms, 42-d feed intake was higher for DEB 240 than for DEB 40. The 21-d weight gain was higher for DEB 240 than for DEB 40 or 140; and 21-d feed/gain was lower for DEB 40 than for DEB 340. The predicted maximum point of inflection for 21- and 42-d weight gains were DEB 250 and 201, with highest 42-d feed intake at 220.

Dietary electrolyte balance for broiler chickens under moderately high ambient temperatures and relative humidities.

Cobb male broiler chicks (1,000) on new litter were used to evaluate effects of dietary electrolyte balance [DEB; Na+K-Cl, milliequivalents (mEq) per kilogram] under tropical summer conditions. Corn-soybean meal-based mash diets had salt (NaCl) alone or in combination with one or more supplements: sodium bicarbonate (NaHCO3), ammonium chloride (NH4Cl), or potassium bicarbonate (KHCO3). A completely randomized design, with five starter and grower feed treatments (control: 145, then 130 mEq/kg; or 0, 120, 240, or 360 mEq/kg throughout) and four replicate pens (1.5 x 3.2 m) per treatment (50 chicks per pen), was used. Diets were analyzed for Na, K, and Cl for confirmation. There were no significant (P < 0.05) effects of treatments on mortality or processing parameters. Water intake increased linearly with increasing DEB, giving higher litter moistures and lower rectal temperatures. Blood HCO3 and pH increased with the highest DEB (360 mEq/kg) causing respiratory alkalosis. The DEB of 240 mEg/kg gave best weight gain and feed conversion ratio, and ideal DEB predicted by regression analyses were 186 and 197 mEq/kg from 0 to 21 d of age and 236 and 207 mEq/kg of feed from 0 to 42 d, respectively. These DEB corresponded to estimated (interpolated) values in predicted optimal 186 to 197 mEq/kg starter of Na 0.38 to 0.40% and Cl 0.405 to 0.39% (K = 0.52%), in 207 to 236 mEq/kg starter, Na 0.409 to 0.445% and Cl 0.326 to 0.372% Cl (K = 0.52%), and in grower Na 0.41 to 0.445%, Cl 0.315 to 0.267% (K = 0.47%).

Influência da suplementaçäo de glutamina sobre o desempenho e o desenvolvimento de vilos e criptas do intestino delgado de frangos / Influence of glutamine supplementation on performance and intestinal villous and crypt development in broiler chickens

Investigou-se o efeito da suplementaçäo de glutamina na dieta sobre o consumo de raçäo, ganho de peso e conversäo alimentar e sobre a estrutura da mucosa intestinal de frangos. Foram utilizados 320 pintos de corte machos distribuídos em um delineamento inteiramente ao acaso com dois tratamentos e quatro repetiçöes, sendo T1 suplementado com 1 por cento de L-glutamina na dieta e T2 controle. Os índices de desempenho foram analisados aos 7, 21 e 49 dias de idade das aves. Aos 7 e 14 dias de idade oito aves foram sacrificadas para colheita de fragmentos de cada porçäo do intestino delgado para avaliaçäo da morfometria intestinal em microscopia de luz em sistema analisador de imagens "Video Plan". As variáveis estudadas foram altura dos vilos, profundidade de cripta e relaçäo vilo: cripta. A adiçäo de 1 por cento de glutamina à dieta de frangos näo influenciou (P>0,05) o seu desempenho zootécnico. Entretanto, 1 por cento de glutamina na raçäo foi capaz de alterar (P<0,01) a altura do vilo, a profundidade de cripta e a relaçäo vilo:cripta no duodeno, bem como a altura de vilo do íleo de frangos no sétimo dia de idade

Níveis de cloreto de sódio em raçöes para frangos de corte / Sodium chloride in broiler diets

Utilizaram-se 1000 pintos de corte para avaliar os efeitos da suplementaçäo de diferentes níveis de cloreto de sódio (NaCl) na raçäo (0,30, 0,45, 0,60, 075 e 0,90 por cento). As aves receberam raçäo e água à vontade com 20,10 e 18,20 por cento PB, 2.900 e 2.950 kcal/kg EM, nas fases inicial e final, respectivamente. Níveis altos de NaCl (0,60, 0,75 e 0,90 por cento) foram efetivos em aumentar o consumo de água e a relaçäo água:raçäo até 21 dias de idade (P<0,05). Na fase de crescimento (21 a 42 dias) apenas o consumo de água aumentou (P<0,05). Os frangos machos apresentaram maior (P<0,05) ganho de peso, consumo de raçäo, mortalidade e consumo de água do que as fêmeas. Nas duas fases de criaçäo, o ganho de peso, o consumo de água, a relaçäo água:raçäo e a umidade de cama aumentaram (P<0,05) quando as aves receberam níveis elevados de NaCl (0,60, 0,75 e 0,90 por cento). A suplementaçäo de níveis elevados de NaCl melhorou o desempenho das aves, afetando negativamente a umidade de cama