Energy metabolism of cocks and broiler chickens fed on diets with different carbohydrate sources.

Energy balances of cocks and chickens were measured using the nitrogen-carbon-balance method. In Experiment 1 twelve adult White Leghorn cocks were fed alternately on a basal ration or on a supplemental ration composed of 75% basal diet and 25% carbohydrate source as a supplement. In Experiment 2 six groups of 12 male broiler chickens were fed successively on two diets each with different carbohydrate sources (40% of DM) and on two energy levels. The investigated carbohydrate sources were glucose, fructose, sucrose, maize starch, raw and steamed potato starch, dried sugar beet pulp, tapioca, wheat, maize, rye and barley. In both experiments the energy digestibility of the diets with raw potato starch, beet pulp and barley was significantly lower compared to the other diets. Digestibility of those ranged from 88 to 81%. By simple linear regression no significant differences in efficiency of utilisation of ME of the diets between the carbohydrate sources sugars, starches and cereal grains could be proved. The corresponding MEm values agreed very close among the diets (411 to 429 kJ.kg BW-0.75.d-1).     

Energy requirements of young female cattle. 6. Energy requirements

Results taken from 6 experiments with young female cattle comprising 477 metabolism periods served the derivation of the animals energy requirement in the development range greater than 125 kg live weight according to the factorial method. The energy requirement per kg LW0.75 and day, calculated from metabolism data, was independent of the stage of development and the intensity of feeding. It averaged 455 +/- 66 kJ metabolizable energy/kg LW0.75.d and 250 +/- 37 kJ NEFcattle/kg LW0.75.d respectively. The partial energy requirement for live weight gain, expressed in net energy fat, was equivalent to the energy content of the live weight gain. Energy retention and thus energy requirement per kg live weight gain increased with the live weight and reached a maximum of 26 MJ. Energy retention per kg live weight gain largely depended on the intensity of feeding and the stage of gravidity. Restrictive energy supply and progressing gravidity decreased energy content in the weight gain. The influences mentioned were taken into consideration on the derivation of the partial requirement for live weight gain. Equations were developed for the estimation of the energy requirement of young female cattle, which can be applied to both gravid and non-gravid cattle.     

The energy metabolism of growing swine in a live weight range of 10-50 kg. 3. Energy maintenance requirement of growing swine]

Investigations into the energy maintenance requirement yielded the following results: For the energy maintenance requirement (EMR) in dependence on live weight (LW) using the relation EMR = aLWb from 13 experiments, an exponent of the live weight of 0.647 +/- 0.054 (0.57 to 0.73) was found out. Increasing the protein content in the feed from approximately 17 to approximately 45% in 6 experiments lowered the energy maintenance requirements about 14, 4, 6, 2, 6 and 12% respectively. The animals' development had no influence on the difference. The amount of the energy maintenance requirement varied greatly between the experiments. Exclusively in the experiments with barrows, a lowest value of 634 and a highest value of 931 kJ metabolizable energy per kg LW0.62.d was measured. On average of 19 comparisons the energy maintenance requirement derived from growth and maintenance periods by means of regression analysis was significant (alpha = 0.05), about 4% higher than the energy maintenance requirement measured on maintenance level directly.     

Comparison of energy deposition and utilization of feedstuffs and rations between growing and adult pigs.

The effect of energy deposition and the utilization of feedstuffs and rations were compared between growing and adult pigs. The good agreement in the data leads to the conclusion, that the energy deposition effect of feedstuffs and rations in growing pigs can be estimated with an equation based on measurements in adult pigs. Exceptions are feedstuffs which are digested bacterially to a relatively high part in the large intestine, as e.g. sugar beet pulp, raw potatoes or similar feed.     

The energetic utilization of rations with dried concentrates, potatoes, sugar beets, apple pectin and cane sugar by growing, intact and ileorectostomized swine. 2. Comparison of results

Results of the measuring of the total metabolism of growing intact pigs (INT) and pigs with ileorectal anastomoses (IRA) are compared. The 16 comparisons are based on studies with rations of dried feedstuffs and rations containing between 30 and 50% of the DM raw or steamed potatoes and sugar beets, sucrose and apple pectin. On an average of all comparisons the relative values for the digestibility of energy, DM and the organic matter as well as for the metabolizability of the energy were between 81 and 82% (values measured at INT animals = 100). The comparison also refers to the crude nutrients, the water-soluble carbohydrates, the starch and the pectin. As a tendency, the IRA utilized the metabolizable energy better than the INT animals. The energy maintenance requirement of the IRA animals was--by 15%--significantly higher than that of the INT animals. There is not yet an answer to the question in how far comparative studies of INT and IRA animals make verified statements with regard to the differences in the energetic utilization of the precaecally and postileally digested nutrients possible. For this, further experiments will be necessary.     

Establishment of woody plants in Mediterranean old fields: opportunity in space and time

The establishment of woody plants following agricultural abandonment in the Mediterranean region is a very widespread process which underlines the extent of the rural exodus. The installation windows in space and time were studied in the French Mediterranean region for two common woody plants, Buxus sempervirens and Fraxinus angustifolia and for a group of common woody fleshy-fruited species. These plants differ in their principal modes of dispersal which are respectively, barochory, anemochory and ornithochory. Their installation was analyzed in relation to the seed shadows, the spatial patterns and the age structures of the seedlings. The majority of the seeds were dispersed over short distances, although some animal vectors may promote a limited amount of long distance dispersal. Hence, whatever the mode of dispersal, a few seeds are often dispersed far from the maternal plant. The combination of several dispersal types in one plant species is a frequently observed feature, one being dominant at a small scale, and related to successional processes, the other being dominant at a larger scale and related to invasive processes. In the old fields the spatial pattern of seedlings closely follow the observed seed shadows. However, competition with the maternal plants may lead to, in some cases, a recruitment deficit close to the seed-bearers. Age structures show that woody plants often install very early after the abandonment of cultivation and that the installation window in time is shortened by the development of a dense herbaceous cover. It is concluded that the installation of woody plants in Mediterranean old fields cannot be reduced to a general rule. The rate and extent of installation depends mainly on the spatial distribution of the seed-bearers, therefore of the spatial patterns of the landscape.     

Dependence of energy maintenance requirements on nutrients in rats. 3. Effect of the protein levels of food on the energy maintenance requirements of growing rats

In addition to earlier experiments with growing rats on the protein levels 10, 25 and 40% crude protein in the dry matter of the feed (Hoffmann et al., 1982 a), two groups of nine male Wistar rats each received feed mixtures with 6 or 25% crude protein resp. and energy metabolism on the energy maintenance level in an N equilibrium or with a positive N balance resp. were measured on 6 levels of live weight between 65 and 250 g and additionally also at subsequent fasting day. Energy maintenance requirement on average of the 6 periods amounted to 381 and 377 kJ metabolizable energy/kg W 0.75 X d on a low or middle protein level resp. and thus did not show changes at the decrease of N retention to values of about zero even with regard to different ATP formation capacities of the nutrients.