Genetic and Environmental Correlations Among Female Fertility Traits and Milk Production in Different Parities of Swedish Red and White Dairy Cattle

The main objective of this study was to estimate genetic correlations between fertility and production traits in first, second and third lactations as well as between fertility traits measured in the same way at different ages. The fertility traits studied were: number of inseminations per service period, number of treatments for reproductive disturbances, interval between first and last inseminations, interval between calving and first insemination, and interval between calving and last insemination. Early milk production was measured as the average of the energy-corrected milk yield at the second and third monthly testdays in a lactation. The number of records was approximately 450 000, 350 000, 180 000 and 75 000 in the heifer period, first, second, and third lactations, respectively. A linear, trivariate model that included the effects of herd-year, year, month, age and sire of the cow was applied. To reduce the effect of ongoing selection, 305-days kg protein production in first lactation was included as a variate in all of the analyses. Correlations between the herd-year effects indicated that factors of herd-year level conducive to increased production had a tendency to increase the number of inseminations as well as the number of reproductive treatments, although there was an earlier start and termination of the insemination period. Genetic correlations between fertility traits and production were in the range of 0.2-0.4, all of them unfavourable and higher at later parities. The genetic correlations between fertility traits in the heifer period and the same traits in first lactation were 0.7. Genetic correlations between the first and second lactation varied between 0.7 and 0.9, and between the second and third lactation they were all 0.9 or higher. In conclusion, fertility and production traits need to be selected for simultaneously if fertility is going to be maintained along further genetic improvement on production, and such selection should include fertility results from lactating cows.     

Antibiotic residues in milk samples obtained from cows after treatment for papillomatous digital dermatitis.

OBJECTIVE: To determine whether there would be detectable antibiotic residues in milk obtained from dairy cattle with papillomatous digital dermatitis (PDD) after topical treatment with oxytetracycline. DESIGN: Randomized controlled clinical trial. ANIMALS: 28 lactating Holstein cows with PDD. PROCEDURE: Cows were assigned to 2 treatment groups. Treatment 1 (n = 16) consisted of spraying of PDD lesions with 15 ml of a solution containing 100 mg of oxytetracycline/ml; lesions were sprayed twice daily for 7 days, using a garden sprayer. Treatment 2 (n = 12) consisted of a one-time application of a bandage that consisted of cotton soaked with 20 ml of a solution containing 100 mg of oxytetracycline/ml. Milk samples were obtained before and after treatment and assayed for tetracycline content by use of high-performance liquid chromatography and a commercially available tetracycline screening test. RESULTS: None of the cows in either treatment group had violative residues of oxytetracycline in milk samples. CONCLUSIONS AND CLINICAL RELEVANCE: Producers treating lactating cows that have PDD, via topical application of oxytetracycline solution at the concentrations reported in this study, have a low risk of causing violative antibiotic residues in milk.     

Control of the weaning-to-estrus interval in sows using gonadotropins and prostaglandins during lactation.

Two experiments were conducted to examine the effectiveness of various strategies using gonadotropins to induce ovulation during lactation as a means of controlling the weaning-to-estrus interval in sows. The objective of Exp. 1 was to examine the efficacy of various gonadotropin regimens for induction of ovulation during lactation. Primiparous (n = 60) and multiparous (n = 83) crossbred sows were assigned, before farrowing, to one of four treatments: no injection (control); 1,000 IU hCG on d 0 (hCG-0; d 0 = day of farrowing); P.G. 600 + 1,000 IU hCG 4 and 7 d after farrowing, respectively (hCG-7); or P.G. 600 + 1,000 IU hCG 11 and 14 d after farrowing, respectively (hCG-14). Sows were weaned on 18 +/- 2 d after farrowing and monitored daily for estrus via exposure to mature boars. The criterion for determining the induction of ovulation was a sustained increase in serum progesterone concentrations above 4.0 ng/mL. The most consistent response to exogenous gonadotropins was on d 0, with an 80% response in primiparous sows (12/15) and a 71% response in multiparous sows (15/21). Weaning-to-estrus intervals for multiparous sows were longer (P = .05) for hCG-14 and hCG-7 than for control and hCG-0 sows. Weaning-to-estrus intervals for primiparous sows were longer (P = .05) for the hCG-14 than for the hCG-0 treatment. The objective of Exp. 2 was to ascertain the effects of postpartum treatment with hCG (1,000 IU) on d 0 and PGF2alpha (10 mg) at d 14 on the weaning-to-estrus interval in multiparous sows weaned at d 14 after birth. Before farrowing, sows (n = 60) were randomly assigned to one of four treatments: positive control, weaning at d 21; negative control, weaning at d 14; hCG within 24 h after farrowing, weaning at d 14; or hCG within 24 h after farrowing and PGF2alpha at weaning, weaning at d 14. Weaning-to-estrus intervals were longer (P = .05) in sows receiving PGF2alpha than in the other treatments. Results indicate that it is possible to induce ovulation immediately after farrowing, using a single injection of hCG, and this strategy can be used to uncouple weaning from the resumption of reproductive activity. However, the administration of PGF2alpha at 14 d after farrowing did not consistently cause regression of the induced corpora lutea.     

Molecular tracing confirms that infection with infectious pancreatic necrosis virus follows the smolt from hatchery to grow‐out farm

Infectious pancreatic necrosis (IPN) is an important restraint to production of salmonids in aquaculture globally. In order to implement efficacious mitigation strategies for control of this disease, it is important to understand infection routes under current production systems. IPN virus has been shown to be transmitted vertically in Rainbow trout, from broodstock to fingerlings in hatcheries, and there is circumstantial evidence suggesting that vertical transmission can also occur in Atlantic salmon, in addition to horizontal transmission between grow‐out fish in farms. In this study, we show that the smolt carries infection with IPN from hatchery to the marine farm. We do this by comparing sequences from fish groups taken both in hatcheries and on corresponding marine grow‐out farms. We use statistical analysis to prove that sequences obtained from the same fish group in both hatchery and marine farm are more similar than sequences obtained from random fish groups on hatcheries and marine farms.     

Impact of three silvicultural treatments on growth,light-energy processing,and related needle-level adaptive traits of Pinus strobus from two regions

Our goal was to quantify and compare the impact of three silvicultural treatments (STs) on growth, light-energy processing, and needle-level morphological adaptive traits for eastern white pine (Pinus strobus L.) from large, central Ontario (ON) and small, isolated Newfoundland (NL) populations. The interest in STs is to reduce weevil (Pissodes strobi) incidence; however, there are potential adaptive changes and productivity trade-offs. The light levels for the STs were, on average, 100%, 42.0%, and 20.4% transmittance for the full-sun, and intermediate- and high-shade STs, respectively. After 8 years, overall height growth was 4.10, 3.25, and 1.70 m for full-sun, and intermediate- and high-shade STs, respectively (P < 0.001). Across all STs, ON populations had greater total height (14%), basal diameter (12%), current leader length (25%), and tree volume (49%) than NL populations (all P < 0.001). At low light levels (10 and 25 μmol m⁻² s⁻¹), high-shade ST trees had higher photochemical quenching (qP) and lower chlorophyll fluorescence (F_pc) compared with intermediate-shade and full-sun STs. At 100 μmol m⁻² s⁻¹ and beyond, full-sun ST trees had higher qP and lower F_pc than intermediate- and high-shade STs. Average total chlorophyll concentration (CHL) and content (CHLC), and carotenoid concentration (CAR), increased in response to the intermediate-shade ST but did not respond further, or decreased in the high-shade ST. Region was significant for CHL, CAR, chlorophyll a:b and CHL:CAR ratios and CHLC, with ON greater than NL, but was reversed for CHL:CAR ratio. Tree height and volume showed a curvilinear and linear relationship to light level, respectively. Tree height showed a positive linear relationship to qP, apparent photosynthesis, chlorophyll a:b ratio, and needle N (all P < 0.001). Tree height showed a negative linear relationship to F_pc, CHL:CAR ratio, specific needle area, C:N ratio, and needle area N⁻¹ (all P < 0.001). There were modest trade-offs between weevil protection and productivity in the intermediate ST due to the compensatory physiological and morphological adaptations to the limiting light, however, the trade-off with growth at the high-shade level was severe. For NL, consideration should now be given to the introduction and mixing of seed from local seed sources with more southern mainland seed sources, which would decrease the inbreeding effect and provide wider variation for natural selection for a more fit future population.     

Critical Thermal Maximum of Juvenile Spotted Seatrout (Cynoscion nebulosus) Reared for Summer Stocking in Texas

The critical thermal maximum of juvenile spotted seatrout (SL range 18–33 mm) was determined using a temperature increase of +0.26°C per hour. The critical thermal maximum (water temperature that was lethal to 50% of the test fish [LT₅₀]) for trial 1 was LT₅₀ = 38.8°C, LT₅₀ = 39.4°C for trial 2, and LT₅₀ = 38.9°C for trial 3. Critical thermal maximums differed significantly (P < 0.05) between trials 2 and 3, whereas trial 1 did not differ among trials. This difference correlated with body size, where fish in trial 2 were significantly larger (P < 0.05) (mean = 27.6 ± 2.0 mm in SL) (mean ± SE) than the fish of trials 1 (mean = 23.1 ± 0.5 mm in SL) and 3 (mean = 21.5 ± 0.7 mm in SL), suggesting positive size dependence in the critical thermal maximum.     

Technological Advances to Address Current Issues in Entomology: 2020 Student Debates

The 2020 Student Debates of the Entomological Society of America (ESA) were live-streamed during the Virtual Annual Meeting to debate current, prominent entomological issues of interest to members. The Student Debates Subcommittee of the National ESA Student Affairs Committee coordinated the student efforts throughout the year and hosted the live event. This year, four unbiased introductory speakers provided background for each debate topic while four multi-university teams were each assigned a debate topic under the theme ‘Technological Advances to Address Current Issues in Entomology’. The two debate topics selected were as follows: 1) What is the best taxonomic approach to identify and classify insects? and 2) What is the best current technology to address the locust swarms worldwide? Unbiased introduction speakers and debate teams began preparing approximately six months before the live event. During the live event, teams shared their critical thinking and practiced communication skills by defending their positions on either taxonomical identification and classification of insects or managing the damaging outbreaks of locusts in crops.     

Efficacy of ivermectin against Dictyocaulus arnfieldi in ponies

The efficacy of orally administered ivermectin against induced Dictyocaulus arnfieldi infection was evaluated in a controlled study comprising 12 yearling ponies. Treatment with ivermectin paste, at a dose rate of 200 micrograms/kg bodyweight orally once, was 100 per cent effective against both adult and immature or inhibited stages of the horse lungworm. Similar control of second and third instars of Gastrophilus intestinalis was observed and no nematode eggs were present in faeces from seven to 15 days after treatment when the study was terminated.