Effect of separating bull semen into X and Y chromosome-bearing fractions on the sex ratio of resulting embryos.

Seventy-six, day 12 to day 15 bovine embryos, collected from 14 donors which had been inseminated with either X or Y chromosome-bearing spermatozoa fractions of semen separated by a thermal convection counterstreaming sedimentation and forced convection galvanization process, were processed for sexing by chromosomal analysis. Fifty-seven embryos were sexed; 20 from Y chromosome-bearing and 37 from X chromosome-bearing fractions of semen. Statistical analysis of the sexing data indicated that there was no significant difference in the male: female ratio for donors receiving male fractions compared to those receiving female fractions. The Y chromosome-bearing fractions produced a male: female ratio that was indistinguishable from the expected 1:1 ratio. However, the X chromosome-bearing fractions of semen produced a highly significant deviation from the expected 1:1 ratio towards the male.     

Effects of continuous low dose infusion of lipopolysaccharide on inflammatory responses,milk production and milk quality in dairy cows

The objective of this study was to evaluate the effects of continuous low dose infusion of lipopolysaccharide (LPS) on inflammatory responses and milk production and quality in lactating dairy cows. Eight Holstein cows were assigned to two treatments in a cross‐over experimental design. Cows were infused intravenously either with saline solution or with saline solution containing LPS from Escherichia coli O111:B4 at a dose of 0.01 μg LPS/kg body weight for approximately 6 hr each day during a seven‐day trial. The clinical symptoms and milk production performance were observed. Milk samples were analysed for conventional components, fatty acids and amino acids. And jugular vein and mammary vein plasma samples were analysed for concentrations of cytokines and acute phase proteins. LPS infusion decreased feed intake and milk yield. An increase in body temperature was observed after LPS infusion. LPS infusion also increased plasma concentrations of interleukin‐1β, serum amyloid A, LPS‐binding protein, C‐reactive protein and haptoglobin. LPS infusion decreased the contents of some fatty acids, such as C17:1, C18:0, C18:1n9 (trans) and C18:2n6 (trans), and most amino acids except for methionine, threonine, histidine, cysteine, tyrosine and proline in the milk. The results indicated that a continued low dose infusion of LPS can induce an inflammatory response, decrease milk production and reduce milk quality.     

A bacterium with close genetic identity to Pseudomonas mandelii associated with spring fish kills in wild bluegill Lepomis macrochirus Rafinesque and pumpkinseed sunfish Lepomis gibbosus (Linnaeus)

Pseudomonas fluorescens are known bacterial pathogens in fish. The P. fluorescens group contains at least nine different bacterial species, although species from fish have rarely been differentiated. Two isolated fish kills affecting wild bluegills, Lepomis macrochirus Rafinesque, and pumpkinseed sunfish, Lepomis gibbosus (Linnaeus), occurred in the spring of 2015 during cool water temperatures (12.5°C–15.5°C). Disease signs included severe bacteraemia with rare gross external signs. Pure bacterial cultures isolated from kidneys of all affected fish were identified as P. fluorescens using the API 20NE system, while no bacteria were isolated from asymptomatic fish. To further identify the species of bacterium within the P. fluorescens complex, genetic analysis of the 16S rRNA, rpoD and gyrB genes was conducted. DNA sequences of bacterial isolates from both mortality events were identical and had close identity (≥99.7%) to Pseudomonas mandelii. Although likely widespread in the aquatic environment, this is the first report of a bacterium closely resembling P. mandelii infecting and causing disease in fish. The bacterium grew at temperatures between 5°C and 30°C, but not at 37°C. It is possible that infections in fish were a result of immunosuppression associated with spring conditions combined with the psychrotrophic nature of the bacterium.     

Embodied Resources in Fish and Shrimp Feeds

Global averages were obtained for amounts of energy, land, water, wildfish, nitrogen, and phosphorus embodied in aquaculture feed ingredients. These data allowed amounts of these embodied resources to be calculated for typical feed formulations for channel catfish, Ictalurus punctatus; hybrid catfish, I. punctatus♀ × I. furcatus♂; Vietnamese catfish, Pangasius spp.; Atlantic salmon, Salmo salar; rainbow trout, Oncorhynchus mykiss; tilapia, Oreochromis spp.; whiteleg shrimp, Litopenaeus vannamei; and black tiger shrimp, Penaeus monodon. Embodied resource use per m.t. of feed varied among species: energy, 4.90–12.48 GJ/m.t.; land, 0.082–0.312 ha/m.t.; water, 502–1227 m³/m.t.; wildfish, 0–2880 kg/m.t.; nitrogen, 3.08–8.63 kg/m.t.; phosphorus, 1.16–5.62 kg/m.t. These calculations did not account for variations in site‐specific factors related to embodied resources and feed composition and use. But they suggest that reducing feed conversion ratio (FCR) by 0.1 unit for the seven species (species groups) could potentially reduce feed use by around 1.1 million tonne (Mt) while conserving 9.8 million GJ of energy, 270,000 ha of agricultural land, 1.4 billion m³ of freshwater, and 1.24 Mt of wildfish. Reduction of the FCR is a powerful means of lessening farm‐level production costs and negative impacts of feed production and use.     

The effects of body composition on the pharmacokinetics of subcutaneously injected ivermectin and moxidectin in pigs

Macrocyclic lactones are characterized by their long persistence in animals because of their extensive distribution into fat. This study examined the influence of body condition on the disposition of ivermectin (IVM) and moxidectin (MXD) in blood and fat following subcutaneous (s.c.) drug administration. 'Fat' and 'thin' lines of pigs were established using two different diets. All animals were then injected with either MXD or IVM at 300 microg/kg and blood samples were taken at regular intervals until slaughter. Two IVM-treated animals from each diet group were slaughtered at either 3 days or 3 weeks posttreatment. Two MXD-treated animals from each diet group were slaughtered at 3 days, 3, 6 or 9 weeks after treatment. Samples of backfat were taken from all animals at slaughter. Fluorescence HPLC was used to determine the concentrations of MXD or IVM in the plasma and fat samples. The plasma IVM concentration peaked more rapidly in the thin IVM treated pigs compared with the fat pigs. The concentration of IVM in backfat was significantly lower in the thin animals slaughtered 3 weeks after treatment. The MXD plasma concentration peaked within the first hour in both the thin and fat groups, but from 12 h posttreatment there was a higher MXD concentration in the plasma of the fat pigs resulting in MXD being detectable in these pigs for 28 days compared with only 17 days in the thin pigs. Despite this difference in plasma persistence no differences were seen in the MXD concentration of backfat between fat and thin animals. Body condition influenced the kinetic disposition of IVM and MXD following s.c. drug administration with both drugs being less persistent in thin compared with fat animals.     

The effect of taurine supplementation to a plant‐based diet for barramundi (Lates calcarifer) with varying methionine content

The effect of variable taurine inclusion (Tau) (1 g/kg DM to 15 g/kg DM) in the diet of juvenile barramundi (Lates calcarifer) on growth and nutrient utilization was investigated at three levels of dietary methionine (Met) supplementation. Diets were fed to juvenile barramundi (starting weight: 26.8 g) twice daily under a restricted pair‐fed regime for a period of 42 days. No significant effect of dietary Tau supply on growth or nutrient utilization was observed at any level of Met inclusion. Numerical variations suggested a positive effect of Tau provision at the mid‐level of supplementation (6–8 g/kg DM). The best‐fit response model (5‐SKM), fitted to the percentage body weight gain data of fish fed diets with an adequate level of Met, suggested a relatively weak pattern of response (R² = 0.183) and predicted a Tau requirement of 5.47 g/kg DM (9.64 g/kg CP) similar to that reported for several other species. It was concluded that taurine appears to be conditionally essential to barramundi, whereby provision in the diet when sulphur amino acid supply is insufficient to meet biosynthetic demands may be beneficial, but that the predicted requirement is likely reasonably accurate for use as a minimum level of inclusion.     

Genetic parameters for litter size,piglet growth and sow's early growth and body composition in the Chinese–European line Tai Zumu

Genetics of piglet growth in association with sow's early growth and body composition were estimated in the Tai Zumu line. Piglet and sow's litter growth traits were calculated from individual weights collected at birth and at 3 weeks of age. Sow's litter traits included the number of piglets born alive (NBA), the mean piglet weight (MW) and the standard deviation of weights within the litter (SDW). Sow's early growth was measured by the age at 100 kg (A₁₀₀), and body composition included backfat thickness (BF₁₀₀). A main objective of this study was to estimate separately the direct genetic effect (d) and the maternal genetic effect (m) on piglet weight and daily weight gain during lactation. Variance components were estimated using the restricted maximum likelihood methodology based on animal models. The heritability estimates were 0.19 for NBA, 0.15 and 0.26 for SDW and MW at 3 weeks and 0.42 and 0.70 for A₁₀₀ and BF₁₀₀. The NBA was almost independent from SDW. Conversely, the A₁₀₀ and BF₁₀₀ were correlated unfavourably with SDW (r_g<−0.24, SE<0.12). A stronger selection for litter size should have little effect on litter homogeneity in weights. Selection for lean growth rate tends to favour heterogeneity in weights. The direct effect on piglet weight at birth and daily weight gain accounted for 12% (h² (d) = 0.02) and 50% (h² (d) = 0.11) of the genetic variance, respectively. The association between d and m for piglet weight was not different from zero at birth (r_g = 0.19, SE = 0.27), but a strong antagonism between d and m for daily weight gain from birth to 3 weeks was found (r_g = −0.41, SE = 0.17). Substantial direct and maternal genetic effects influenced piglet growth until weaning in opposite way.     

Novel insights into the marine phase and river fidelity of anadromous twaite shad Alosa fallax in the UK and Ireland

1. Most research on anadromous fishes has been invested in their freshwater life‐phases, resulting in a relatively sparse understanding of their spatial ecology during marine life‐phases. However, understanding the marine dispersal of anadromous fishes is essential to identify threats and to implement conservation measures that fully encompass their lifecycle.
2. The twaite shad Alosa fallax is an anadromous fish increasingly imperilled across its range due to pollution, harvesting, and impediments to freshwater migration, but little is known about its distribution and movements during its marine life‐phase. Here, the application of acoustic telemetry provided novel insights into the coastal dispersal of twaite shad in the UK and Ireland during 2018–2019, and the freshwater entry of individuals during the 2019 spawning season.
3. Of 73 twaite shad acoustic‐tagged during their upstream migration in the River Severn in May 2018, 58 emigrated from the river. Twelve were subsequently detected 200 km to the south‐west at the Taw–Torridge Estuary between July 2018 and April 2019, where estuarine movements up to 5.8 km inland occurred in summer, winter, and spring. One was subsequently detected in the Munster Blackwater Estuary (Ireland) and then in the River Severn, indicating a minimum movement distance of 950 km. Thirty‐four (59%) of the emigrating individuals from 2018 re‐entered fresh water in the rivers Severn (n = 33) and Wye (n = 2) in April and May 2019.
4. These results suggest year‐round use of estuarine and nearshore habitats by at least a subset of the twaite shad population during their marine phase, providing evidence of potential range overlap between populations that spawn in different areas in the UK and Ireland, which may be facilitated by substantial dispersal. The results also highlight the potential of telemetry for estimating freshwater and marine mortality, and the benefits of sharing detection data across networks.

     

A conservation-tillage, cover-cropping strategy and economic analysis for creamer potato production

A two-year experiment was conducted at the Beltsville Agricultural Research Center (BARC), MD, and Virginia Polytechnic Institute and State University Kentland Agricultural Research Farm (KARF), VA, to evaluate potato (Solanum tuberosum L.) production of 32- to 57-mm-size-range tubers (referred to hereafter as creamers) in a conservation-tillage, cover-cropping strategy. The experiments used a split-plot design in which the main-plots were cover crop treatments and the sub-plots were different potato selections. Main plot treatments included rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), Austrian winter pea (Pisum sativum L.), rape (Brassica napus L.), oat (Avena sativa L.), rye/crimson clover mixture, rape/crimson clover mixture, bare soil/raised beds, and bare soil/flat beds (control). Potato selections tested were B1145-2, B1491-5, and B1492-12 in 2000 and B1145-2, B1102-3, and B0811-4 in 2001. Yields in the conservation-tillage treatments were equal to or better than those in the bare soil/flat bed control with few exceptions. Large-sized tubers (<57 mm) in almost all cases remained below 6% of total marketable yield even when the tubers were harvested late. Delayed harvest did not reduce creamer-sized yields nor did it increase yield of large-sized tubers. Economic analysis shows that net returns from some conservation-tillage treatments are equal to or higher than the conventional-tillage strategy and confirms the viability of the conservation-tillage, cover-cropping strategy. Furthermore, the conservation-tillage strategy in many cases allows timely planting using machinery in the wet soils of Maryland and Virginia during the narrow window of spring potato planting time, whereas the conventional tillage strategy does not offer this advantage.