Nutritive value of forages as affected by soil and climatic differences

Wintering and finishing performances of beef steers have been compared at Colby, Garden City, Manhattan and Mound Valley. When feeds were grown locally, cattle at Garden City and Colby outperformed those at Manhattan and Mound Valley (Bulletin 507, 1967). Since all cattle were of the same origin, differences were credited to the climate and/ or feed composition. In 1968-9 (trials 5 and 6), cattle were fed at all locations on feed produced at Garden City. During the wintering phase in trial 5, cattle at Colby and Garden City significantly outgained those at Mound Valley (P<.0l). Performance at Manhattan was intermediate. In trial 6, table 18, during wintering, steers at Manhattan gained faster (P<.01) than those at Colby or Garden City but not those at Mound Valley. Finishing gains did not differ significantly in either trial. Results of the last two tests being more uniform than results of the previous four indicates some of the differences are from the site where the feed is produced

Seed production and seed quality of the dune building grass Panicum racemosum Spreng

Seed production, pollination requirement, seed characteristics related to quality and the relationship between number and mass of seeds were examined for Panicum racemosum in three successional populations in southern Brazilian coastal dunes. The seed production was generally low and declined further between the frontal dunes and the backdunes, dropping from 4.05 seeds per panicle in the former to 1.8 seeds in the latter. However fertility (% fertile florets) did not differ among the three habitats. Plants cross-pollinated in a glasshouse showed an increase in seed production to 41.4 seeds compared to no seed production in self-pollinated plants. Caryopses varied in mass from 3.2 to 12.2 mg with a mean of 7.98 mg. A strong negative correlation was found between mean individual seed mass and the total number of seeds per panicle in a natural population. However, this relationship did not persist in seeds produced by cultivated plants in the glasshouse. The causes of low seed production appear to be mainly pollen self-incompatibility and additionally competition for nutrients between sexual reproduction and allocation to clonal growth. Under conditions of nutrient shortage, Panicum racemosum probably allocates resources more to clonal growth and to fewer, but well-endowed seeds. This would permit emergence from deeper burial sand, faster growth and greater survival of seedlings

Fontes de carboidratos e ionóforo em dietas contendo óleo vegetal para ovinos: digestibilidade, balanço de nitrogênio e fluxo portal de nutrientes Carbohydrate sources and ionophore in sheep diets with vegetal oil: digestibility, nitrogen balance and portal flux of nutrients

Os objetivos neste trabalho foram avaliar a utilização de duas fontes de carboidratos (casca de soja e milho), com a utilização ou não de monensina em dietas com alta densidade lipídica, e seus efeitos sobre a digestibilidade dos nutrientes, o balanço de nitrogênio e o fluxo portal de nutrientes em ovinos. Adotou-se o método de coleta total de fezes e urina para determinação da digestibilidade e do balanço de nitrogênio. O fluxo líquido de nutrientes foi calculado pelo princípio de Fick. Foram utilizados quatro ovinos (54 kg de PV) da raça Corriedale com três cateteres implantados (veia e artéria mesentérica e veia porta). A ingestão, a excreção fecal, a digestão e a digestibilidade de MS, MO e EE não foram influenciadas pelos tratamentos. A ingestão, a digestão e a digestibilidade da FDN foram maiores para as dietas com casca de soja (757,0; 531,1 g/dia e 70,2%) que para aquelas com milho (392,3; 199,9 g/dia e 51,0%), enquanto a dos carboidratos não-fibrosos (CNF), foram maiores para as dietas com milho (474,6, 416,8 g/dia e 87,8%) que para aquelas com casca de soja (148,0; 97,8 g/dia e 66,1%). A concentração de energia expressa como NDT foi maior nas dietas com milho (80,2%) que naquelas com casca de soja (76,7%). Não houve efeito da utilização da monensina nos parâmetros de digestibilidade e balanço de nitrogênio. A excreção fecal da proteína foi menor e a digestibilidade maior para as dietas com milho. A concentração portal e arterial de nitrogênio alfa amino (N alfa-amino) foi menor para as dietas com monensina (3,161 e 2,922 e 3,530 e 3,218 mM, respectivamente). A concentração portal (0,419 vs 0,516 mM), a diferença venosa-arterial (0,230 vs 0,317 mM) e o fluxo portal de amônia (26,119 vs 37,041 mM/h) foram menores para as dietas com milho.<br>The objectives of this trial were to evaluate the effects of two carbohydrate sources (soybean hulls and corn grain) with and without monensin on digestibility, nitrogen balance and portal nutrient flux in sheep fed high vegetable oil diets. Four Corriedale wethers averaging 54 kg of body weight and fitted with catheters in the mesenteric and portal veins and also in the mesenteric artery were used. Digestibility and nitrogen balance were determined using total collection of feces and urine. Net nutrient flux was calculated using the Fick principle. Intake, fecal excretion, digestion and digestibility of dry matter (DM), organic matter (OM) and ether extract (EE) were not affected by treatments. However, intake, digestion and digestibility of neutral detergent fiber (NDF) were higher when animals were fed soybean hulls (757.0 g/d, 531.1 g/d and 70.2%) rather than corn grain (392.3, 199.9 g/d and 51.0%). Conversely, intake, digestion and digestibility of nonfiber carbohydrates (NFC) as well as TDN content were greater on corn (474.6 g/d, 416.8 g/d, 87.8%, 80.2%) than on soybean hulls diets (148.0 g/d, 97.8 g/d and 66.1%, 76.7%). There was no effect of monensin on nutrient digestibility and nitrogen balance. Fecal excretion of protein was lower and protein digestibility was higher for corn diets. Alpha-amino-nitrogen concentration in arterial and portal plasma was lower for diets supplemented with monensin (3.161 and 2.922 mM) compared to non-supplemented monsesin diets (3.530 and 3.218 mM), respectively. Portal concentration (0.419 vs. 0.516 mM), venous-arterial difference (0.230 vs. 0.317 mM), and portal flux (26.119 vs. 37.041 mM/h) of ammonia were all lower on corn diets