Stable isotopes and gut content show diet overlap among native and introduced piscivores in a large oligotrophic lake

Abstract – In past dietary studies kokanee Oncorhynchus nerka were prominent in the diet of Pend Oreille Lake's large piscivores: native bull trout Salvelinus confluentus, cutthroat trout O. clarki and northern pikeminnow Ptychocheilus oregonensis, and introduced lake trout S. namaycush and Kamloops rainbow trout O. mykiss gairdneri. However, kokanee have declined to 10–20% of their former abundance. We therefore initiated this study to understand current predation demands on kokanee and diet overlap among piscivores, using gut content samples and analysis of stable nitrogen (δ¹⁵N) and carbon (δ¹³C) isotopes from the lake's fish and invertebrate community. In gut content samples, kokanee were the main prey item of large [i.e., ≥400 mm total length (TL)] bull and lake trout; a conclusion that was affirmed by stable isotope analysis. Rainbow trout >500 mm TL consumed mostly kokanee, thus there was a high degree of diet overlap among large bull, lake and rainbow trout. Small (i.e., <400 mm TL) rainbow and cutthroat trout diets overlapped, and were composed mostly of littoral benthic invertebrates. However, gut content and stable isotope analysis did not accord for 400–500 mm TL rainbow trout, small lake trout, and large cutthroat trout. In these instances, a linear mixing model using stable isotope results predicted kokanee consumption for each species, but no kokanee were identified in rainbow or lake trout gut content. Gut content and stable isotope analysis of native northern pikeminnow indicated a diet of mostly littoral benthic invertebrates at smaller (100–150 mm TL) lengths, with kokanee becoming more prominent in the diet of individuals >300 mm TL. Percent of kokanee in the diet of northern pikeminnow has declined from a prior study; otherwise piscivore diets have apparently remained unchanged. In this study, judgments as to the feeding of some piscvores, based on gut content alone, would be tenuous because of small sample sizes, but stable isotope analysis provided an efficient means for confirming diets.     

Experiences with Rice Grown on Permanent Raised Beds: Effect of Crop Establishment Techniques on Water Use,Productivity, Profitability and Soil Physical Properties

In recent years, conventional rice production technologies have been leading to deterioration of soil health and declining farm profitability due to high inputs of water and labor. Conservation agriculture(CA) based resource-conserving technologies i.e. zero-tillage(ZT), raised-bed planting and direct-seeded rice(DSR) have shown promise as alternatives to conventional production technologies to overcome these problems. Present study was undertaken during 2009–2012 to establish an understanding of how permanent raised bed cropping system could be practiced to save water at the field application level to improve water productivity and also have the capability to enhance productivity, profitability and soil physical quality. The results showed that among different crop establishment techniques, conventional-tilled puddle transplanted rice(CT-TPR) required 14%-25% more water than other techniques. Compared with the CT-TPR system, zero till direct-seeded rice(ZT-DSR) consumed 6%–10% less water with almost equal system productivity and demonstrated higher water productivity. Wide raised beds saved about 15%–24% water and grain yield decrease of about 8%. Direct-seeded rice after ZT or reduced tillage or on unpuddled soil provided more net income than CT-TPR. The CTTPR system had higher bulk density and penetration resistance due to compaction caused by the repeated wet tillage in rice. The steady-state infiltration rate and soil aggregation( 0.25 mm) were higher under permanent beds and ZT and lower in the CT-TPR system. Under CT-TPR, soil aggregation was static across seasons, whereas it improved under no-till and permanent beds. Similarly, mean weight diameter of aggregates was higher under ZT and permanent beds and increased over time. The study reveals that to sustain the rice productivity, CA-based planting techniques can be more viable options. However, the long-term effects of these alternative technologies need to be studied under varying agro-ecologies in western Uttar Pradesh, India.     

Effect of soybean meal substitution by different concentrations of sunflower meal on egg quality traits of white and coloured dwarf dam lines

1. The effect of soybean meal substitution by different concentrations of sunflower meal on egg quality traits of white and coloured dwarf dam lines was investigated.

2. A total of 144 dwarf hens (38 weeks of age) from the same hatch were randomly divided into 12 groups of 12 birds (4 dietary treatments × 3 replicates).

3. A 2 × 4 factorial design was used to study the effect of 2 lines (Factor A) and substitution of soybean meal (SBM) with 4 concentrations (0, 10, 15 and 20%) of sunflower meal (SFM) [Factor B] on egg quality traits of dwarf dam line hens.

4. All the diets were designed to be isocaloric (11?3 MJ ME/kg) and isonitrogenous (180 g/kg crude protein) The duration of the experiment was 12 weeks.

5. Analysis of variance indicated a highly significant line effect. There were non-significant effects of substitution of soybean meal with different concentrations of sunflower meal on egg quality traits except for Haugh unit.

6. White plumaged dwarf broiler breeder dam line produced significantly fewer, but larger, eggs than coloured dwarf dam line hens.     

The effect of extended grazing time and supplementary forage on the dry matter intake and foraging behaviour of cattle kept under traditional African grazing systems

An experiment was carried out at Alemaya University in Ethiopia to investigate the effect of night kraaling on the dry matter intake (DMI), live weight gain (LWG) and foraging behaviour of Ogaden cattle. Three groups of four animals were given either 7 h access to pasture per day, simulating traditional grazing (TG) practice; extended grazing (EG) access for 11 h per day; or traditional grazing access plus a nocturnal forage supplement (TF). Live weight gain, DMI and foraging behaviour were measured during the late dry season (EP1) and the wet season (EP2). None of the treatments had any significant effect on either DMI or LWG during EP1 or EP2. Extending pasture access time from 7 h to 11 h did not significantly increase the amount time spent grazing, but grazing intensity was significantly (p < 0.05) reduced during the non-common grazing hours. Step rate was significantly lower (p < 0.01) during EP2 than during EP1 and bites per step were significantly higher (p < 0.001) during EP2 than EP1, indicating that animals had to travel a shorter distance before selecting material to eat during the wet season (EP2). Providing supplementary forage (TF) had no significant effect on any measured parameter. In this study neither of the two low-cost methods (EG and TF) of improving access to forage had any beneficial effect on cattle productivity. It is concluded that, under the prevailing conditions, the traditional grazing practices of this part of Ethiopia do provide sufficient pasture access time to achieve daily voluntary food intake.     

Alterations in calcium, phosphorus and C-terminal parathyroid hormone levels in equine acute renal disease

The changes in serum and urinary levels of calcium and phosphorus and serum parathyroid hormone (PTH) were studied during controlled, chemically induced, acute renal disease in 4 ponies. There was an initial rise in daily urinary calcium and hydroxyproline excretion in 2 ponies which may have indicated increased bone resorption. Mild hypercalcemia, hypophosphatemia and elevated C-terminal PTH levels were associated with oliguria. Total daily urinary excretion of calcium and phosphorus decreased as oliguria developed. The levels of C-terminal PTH were increased in all four animals. This appears to have been related to their diminished renal function in that C-terminal fragments of intact PTH (which require functioning kidneys in order to be cleared) were probably being accumulated. Although there was no evidence with regard to an actual increase in PTH secretion, prolongation of intact PTH half-life due to renal tubular damage may have contributed to the development of hypercalcemia.     

Swinepox--skin disease with sporadic occurrence

Swinepox virus infection results in an acute, mild or subclinical course and is characterised by typical poxvirus skin lesions in affected pigs. Additionally, sporadic vertical swinepox virus transmission leads to congenital generalised infection and subsequent abortion or stillbirth. The present report describes the occurrence of epidermal efflorescences in two piglets after intrauterine natural suipoxvirus infection. No clinical abnormalities of the gilt and littermates as well as in other pigs from this herd were present. One of the affected piglets was stillborn and submitted for necropsy, the other animal was alive at birth, but died 3 days later. Histologically, a proliferative to ulcerative dermatitis with epithelial ballooning degeneration and characteristic intracytoplasmatic inclusion bodies was observed. The pathomorphological and histopathological suspected diagnosis of a poxvirus infection was confirmed by electron microscopy. Furthermore, the agent was identified as suipoxvirus by polymerase chain reaction. As demonstrated here, obvious skin lesions in suipoxvirus infection leads to a suspected diagnosis in newborn piglets on macroscopic examination. However, further post mortem examinations, including electron microscopy as well as molecular techniques are essential for the identification of the aetiology and the exclusion of differential diagnoses. Because the disease only affected two pigs there was only a small economic loss. A valid diagnostic plays an important role in advising farmers and for herd health monitoring.     

Consumption of Low Larkspur (Delphinium nuttallianum) by Grazing Sheep

Low larkspur (Delphinium nuttallianum Pritz.) poisoning causes serious economic loss to livestock producers that graze cattle on foothill and mountain ranges in western North America. In general, all Delphinium spp. are five times less toxic to sheep than to cattle. Because low larkspurs are less toxic to sheep than cattle, grazing sheep before cattle on rangelands with dense populations of low larkspur can reduce larkspur density and risk of poisoning to grazing cattle. All previous published work on sheep and larkspur interactions has involved tall larkspurs. This series of studies was conducted to determine if sheep would consume sufficient low larkspur to reduce subsequent risk to cattle. Four summer trials were conducted in Collbran, Colorado, and Soda Springs, Idaho on pastures with dense (> 9 plants · m^?2) low larkspur populations. In all trials, sheep ate very little low larkspur (< 0.5% of bites). During one final trial using high sheep density (two sheep · 0.015 ha^?1 for 9 d), sheep consumed little low larkspur, but animals appeared to trample much of the low larkspur. Toxic alkaloid concentrations in low larkspur ranged from 1.1 mg · g^?1 to 1.6 mg · g^?1 in all trials. The use of sheep to graze low larkspurs to reduce subsequent consumption by grazing cattle does not appear to be a viable option.     

Reproductive, metabolic, and endocrine responses to feed restriction and GnRH treatment in primiparous, lactating sows

The current experiment was carried out to determine whether exogenous GnRH treatment in primiparous, lactating sows undergoing feed restriction would improve reproductive performance after weaning. Sows were allocated to one of three treatments: AA sows (n = 8) were fed to appetite throughout a 28-d lactation, AR (n = 12) and AR + GnRH (n = 12) sows were fed as AA sows from farrowing to d 21 of lactation, and feed intake was reduced to 50% of the ad libitum intakes from d 22 to 28. The AR + GnRH sows received 800 ng of GnRH i.v. every 6 h from d 22 to 28 of lactation, and AA and AR sows received saline. Sow weight, backfat, and litter weight were recorded weekly. Within 2 d after farrowing, litter size was standardized to 8 to 10. At d 17 of lactation, an indwelling jugular catheter was surgically implanted in each sow. Blood samples were taken for characterization of plasma LH, FSH, insulin, IGF-I, and leptin by RIA at d 21 and before and after weaning on d 28 of lactation. After weaning, all sows were given ad libitum access to feed, checked for onset of standing estrus twice daily with mature vasectomized boars, and inseminated 12 and 24 h after onset of standing estrus with pooled semen from the same fertile boars (3 x 10(9) sperm/AI). After breeding, feed allowance was reduced to NRC (1988) requirements for gestation. At d 28 +/- 3 of gestation, sows were killed and ovulation rate and embryo survival were determined. Restricted sows lost more weight during lactation than AA sows (P < .02). During the period of feed restriction, plasma IGF-I and postprandial insulin and leptin in AR and AR + GnRH sows, and LH pulse frequency in AR sows, were lower than those in AA sows (P < .04). Associations (P < .004) between plasma insulin and leptin and between leptin and mean LH concentrations were established. The LH pulse frequency in AR + GnRH sows did not differ from that in AA sows before weaning. After weaning, maximum, mean, and minimum LH concentrations in the AA and AR sows, and FSH concentrations in AR sows, increased (P < .05) in response to weaning. Paradoxically, GnRH treatment in lactation seemed to suppress the expected LH and FSH responses to weaning. Ovulation rate and embryo survival were not different among the three groups. In conclusion, although exogenous GnRH therapy restored LH secretion in feed-restricted sows, it did not improve overall reproductive performance.     

Geographical variation of the skull morphology of the common tree shrew (Tupaia glis).

Geographical variation was examined morphologically in the common tree shrew (Tupaia glis) in some Indochinese and Malayan regions. Osteometrical examination and principal component analysis elucidated the morphological differences among various populations. The populations from southern and western Thailand were distinguished morphologically from the other populations. Variation in males from south Thailand and Kuala Lumpur suggests that the Isthmus of Kra may have an influence on the variation of skull morphology. However, the Isthmus of Kra was not completely considered as a factor of geographical separation in this species, because we could not confirm the separation in skull size and shape between the localities at least in females. While, the Kanchanaburi population in western Thailand was significantly smaller than the other population in skull size, and constituted the morphologically separable group in our study.     

The effect of dietary chloride and bicarbonate on blood pH, haematological variables, pulmonary hypertension and ascites in broiler chickens.

1. The effect of supplementing grower diets with bicarbonate or chloride on haematological variables, pulmonary hypertension syndrome and ascites in broilers exposed to cold temperature was investigated. 2. High concentrations of dietary chloride had no effect on the pH of the venous blood but a low chloride/high bicarbonate diet significantly increased blood pH. There was no consistent effect of dietary chloride or bicarbonate concentrations on growth performance, although in 1 experiment birds given a low chloride/high bicarbonate diet consumed less food and gained less weight than controls. 3. Birds fed on high-chloride diets tended to have a higher incidence of ascites and pulmonary hypertension than controls. Birds fed on low-chloride and high-bicarbonate diets had significantly lower pulmonary hypertension and lower heart weights, which may have indicated a decrease in pulmonary and systemic blood pressure. 4. We conclude that increasing dietary bicarbonate and reducing dietary chloride has potential as a low cost and effective method to reduce the pulmonary hypertension which leads to ascites in broiler chickens.