Some attempts to improve the nutritive value of urea for dairy cows. 3. Its adjunction to fermentable carbohydrates: starea

Starea, an intimate mixture of gelatinized wheat starch and urea, was tested again urea with regard to the ammonia release in the rumen, the amount and composition of the nitrogen fraction reaching the intestine, the nitrogen and energy balances, and the performance of lactating cows. Maize silage was the basal feed in all experiments. The ammonia concentration in the rumen liquor was measured in two cows fitted with a permanent rumen cannula. The curve of the ammonia concentration was about the same with both nitrogen supplements, and peaked at about 250 mg/l (14.7 mmol/l) two hours postfeeding. Two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus were fed with maize silage supplemented with increasing amounts of either urea or starea. The duodenal nitrogen flow rapidly levelled off with both supplements and no significant difference between them could be detected. The amount of ammonia in the duodenal digesta remained very low. Nitrogen digestibility measured in lactating cows was not noticeably affected when starea instead of urea was added to maize silage. However, nitrogen excretion in the urine tended to decrease, while nitrogen secretion in milk was augmented with starea. The digestibility of the rations and their metabolizable energy supply were not significantly affected, and milk production was quite the same with both supplements, apart from the higher amount of milk protein obtained with starea compared with urea. As a general conclusion from the whole work conducted on the nutritive value of urea for lactating cows, it can be stated that the decline in performance of the animals after substitution of urea for conventional protein is mainly due to a decrease of the metabolizable energy concentration in the diets. None of the attempts tested in an effort to improve the nutritive value of urea was able to overcome this difficulty.     

Pheromone Concentration as a Mechanism for Reproductive Isolation between Two Lepidopterous Species

Pheromone-releasing females of the closely related noctuid moths Trichoplusia ni and Autographa californica attract mainly males of their own species. Sex-pheromone-concentration specificity appears to be an important reproductive isolating mechanism for these two species. Apparently, both species utilize the same pheromone, cis-7-dodecenyl acetate, for mating communication, but T. ni utilizes a higher level than does A. californica. Traps releasing amounts of cis-7-dodecenyl acetate that are highly attractive for males of one of the species catch very few males of the other species.     

堆肥及消化对城市污泥中LABs降解行为的初步研究

对广州、深圳两城市污泥及经消化和堆肥化的污泥中ＬＡＢｓ的检测和分析表明：（１）两城市污泥中ＬＡＢｓ化合物均为合成来源,但二者的配方不同．（２）厌氧消化和好气堆肥两种处理对同碳数的ＬＡＢ所有异构体降解程度基本相近,但不同异构体之间降解速度不同,２－苯基异构体优势于其它异构体降解．（３）两种生污泥都已经历了较高程度的降解,好气堆肥能使有机质降解程度提高,而厌氧消化作用则不能．新降解程序指标［Ｉ／Ｅ］１３的有效性有待进一步研究．     

Assessment of repeated application of poultry litter on phosphorus and nitrogen dynamics in loblolly pine: Implications for water quality

The Southeastern United States has a robust broiler industry that generates substantial quantities of poultry litter as waste. It has historically been applied to pastures close to poultry production facilities, but pollution of watersheds with litter-derived phosphorus and to a lesser extent nitrogen have led to voluntary and in some areas regulatory restrictions on application rates to pastures. Loblolly pine (Pinus taeda L.) forests are often located in close proximity to broiler production facilities, and these forests often benefit from improved nutrition. Accordingly, loblolly pine forests may serve as alternative land for litter application. However, information on the influence of repeated litter applications on loblolly pine forest N and P dynamics is lacking. Results from three individual ongoing studies were summarized to understand the effects of repeated litter applications, litter application rates, and land use types (loblolly pine forest and pasture) on N and P dynamics in soil and soil water. Each individual study was established at one of three locations in the Western Gulf Coastal Plain region. Annual applications of poultry litter increased soil test P accumulation of surface soils in all three studies, and the magnitude of increase was positively and linearly correlated with application rates and frequencies. In one study that was established at a site with relatively high soil test P concentrations prior to poultry litter application, five annual litter applications of 5 Mg ha⁻¹ and 20 Mg ha⁻¹ also increased soil test P accumulation in subsurface soils to a depth of up to 45 cm. Soil test P accumulations were greater in surface soils of loblolly pine stands than in pastures when both land use types received similar rates of litter application. In one study which monitored N dynamics, lower soil organic N, potential net N mineralization, potential net nitrification, and soil water N was found in loblolly pine stands than pastures after two annual litter applications. However, increases in potential net N mineralization, net nitrification, and soil water N with litter application were more pronounced in loblolly pine than in pasture soils. Loblolly pine plantations can be a viable land use alternative to pastures for poultry litter application, but litter application rate and frequency as well as differences in nutrient cycling dynamics between pine plantations and pastures are important considerations for environmentally sound nutrient management decisions.     

The value of species rarity in biodiversity recreation: A birdwatching example

Wildlife viewing recreation offers conservationists opportunities for education and generating revenue but can also have detrimental ecological impacts. To manage these opportunities and impacts effectively, a better understanding is needed of what people value in wildlife viewing events. We examine the relationship between species rarity and value for wildlife viewing recreation. We undertook visitor counts of birdwatchers attending rare (vagrant) bird sightings and collected home postcodes to assess the distances these individuals travelled to achieve these sightings. We also undertook visitor counts at common bird viewing locations for comparison. We regressed birdwatcher numbers against rarity, site protection status, time the bird had been on site and day of the week when the count took place. We undertook these analyses for rare bird sightings only, using a continuous measure of rarity, and for both rare and common species combined, using a categorical rarity index. Species rarity was the clearest predictor of visitor numbers in both the analyses. When studying rare birds only, we found the functional form of the relationship between rarity and visitor numbers to be inverse and asymptotic. Individuals also travelled further to see rarer species. However, while exceptional numbers of visitors attended exceptionally rare bird sightings, the marginal value of rarity appeared to be relatively low. Despite the opportunity for revenue raising and education provided by rare bird sightings, a comparison of visitor numbers at sightings inside and outside protected areas showed no evidence that managers of protected areas capitalise on these opportunities.     

Some attempts to improve the nutritive value of urea for dairy cows. II. Its administration in a slightly soluble form: isobutylidene diurea (IBDU)

Isobutylidene diurea (IBDU) was tested against urea with regard to the ammonia release in the rumen, the amount and composition of the nitrogen fraction reaching the intestine, the nitrogen and energy balances and the performance of lactating cows. Maize silage was the basal feed in all experiments. The ammonia concentration in the rumen liquor was measured in two dry cows fitted with a permanent rumen cannula. The ammonia release was clearly restrained when IBDU was substituted for urea, and the peak values were of the same order as those found with soybean meal. Two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus were fed with maize silage supplemented with increasing amounts of either urea or IBDU. The duodenal flow levelled off with urea, but it continued to rise with IBDU even when high amounts were added to the silage. However, a large fraction of this increase was in the form of ammonia, corresponding to 60% of the dietary nitrogen supplied by IBDU. The amount of non-ammonia nitrogen was also higher with IBDU. The nitrogen balance of lactating cows was not noticeably affected when IBDU instead of urea was added to the maize silage. In the same manner, the digestibility of the rations and their metabolizable energy supply were not significantly modified, and the milk productions were quite similar with the two N compounds, apart from the tendency to lower milk fat and milk protein productions.     

Cumulative selectivity benefits of increasing mesh size and using escape gaps in Australian Portunus armatus traps

The individual and cumulative effects of increasing mesh size (from 56‐ to 75‐mm stretched mesh opening) and installing three escape gaps (36 × 120 mm) in collapsible‐netted round traps were assessed to address concerns associated with excessive discarding in an Australian portunid fishery. Compared to conventional traps comprising 56‐mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer (by 54%) undersized blue swimmer crabs, Portunus armatus Milne‐Edwards and yellowfin bream, Acanthopagrus australis Günther (by 64%). Irrespective of escape gaps, simply increasing the mesh size to 75 mm did not significantly affect catches of undersized P. armatus, although 87% fewer A. australis were retained. Traps with both 75‐mm mesh and escape gaps maintained reductions of A. australis, but had a clear cumulative effect on P. armatus selection, retaining 84% fewer undersized individuals across a larger size at retention. The results support using escape gaps in existing conventional traps, but illustrate the need to configure the minimum legal mesh size to approach the desired target size of P. armatus as a precursor to maximising trap selectivity. Larger‐meshed traps also require less material (i.e. plastic), which benefits their manufacture and, equally importantly, reduces environmental costs when lost.     

Alterations of offspring heart muscle electrical activity transferred by rat male genitors chronically treated with lindane (γ-hexachlorocyclohexane) trace concentrations

Using intracellular microelectrodes, we studied transmembrane resting and action potentials (AP) of left ventricle papillary muscles isolated from the heart of adult lindane-treated (TMG) and untreated (UMG) male genitor rat offspring, obtained by mating untreated female with males chronically treated and untreated with lindane (2 ppb) trace concentrations through beverage. The AP magnitude and duration (APD) were similar in both groups and their response to low temperature (22 °C) unchanged. Lowering the external Ca²⁺ concentration from 2.5 to 0.625 mM prolonged APD in the TMG group but not in the UMG group. In the TMG group, (i) cumulative addition of Sr²⁺ (1 mM) to the physiological solution prolonged APD; (ii) apamin (4 μM) and charybdotoxin (4 μM) prolonged the APD. In conclusion, our data revealed that an altered sensitivity of the Ca²⁺-induced Ca²⁺ inactivation of L-type Ca²⁺ channels and of Ca²⁺-activated K⁺ channels to Ca²⁺ has been transferred to TMG offspring.     

Acute phase proteins assessment for an early selection of treatments in growing calves suffering from bronchopneumonia under field conditions

Blood samples were taken from calves with respiratory disease the first day of examination for determination of the serum concentration of haptoglobin, fibrinogen, alpha-2- and gamma-globulins, and albumin. A clinical examination was performed daily for the duration of the disease. The animals were retrospectively classified in two categories: those animals requiring no treatment or antibiotics alone (group A), and antibiotics associated to anti-inflammatory drugs (group B). The serum proteins were tested in order to check whether they were able to distinguish, on the first day of clinical examination, between calves requiring anti-inflammatory treatment (group B) or not (group A). About 80% of calves were properly classified in both groups by the combined use of the two serum proteins haptoglobin and fibrinogen: these two proteins, and especially haptoglobin, were useful for the identification of calves requiring an anti-inflammatory treatment.