Evaluation of Breeding Value and Selection of Bull Dams in the Danish Dairy Breeds: I. Studies on Realized Efficiency of Bull Dam and Bull Sire Selection

Abstract

The relationship between twice the adjusted daughter yield deviation (DYD) of the son and the average of the estimated breeding values (EBV) of his parents was investigated for milk and fat yield. Deviations from expectations of DYD minus the pedigree index and the regression of DYD on the EBV for each of the parents were estimated. The EBV of each bull dam was calculated in several ways using different combinations of pedigree information and their own records. In all, 1693 bulls (880 Black and White (BW), 418 Red Danish (RD) and 395 Danish Jersey (DJ)) with Direct Updating indices for milk and fat yield were included in the investigation. Mean discrepancies between estimated and observed genetic merit for kg of milk yield were ?348 for BW, ?213 for RD and ?228 for DJ, when all of the bull dams' individual records were utilized in breeding value estimation. The corresponding mean discrepancies for kg of fat yield were ?14.7, ?11.5 and ?11.9, respectively. The discrepancies were positively correlated with the number of lactation records included in the dams' EBVs. Regression coefficients of bull DYDs on bull dam breeding values were significantly lower than expected for RD and BW regardless of the number of individual lactation records included in the dams' indexes for milk and fat yield. For all three breeds, the regression coefficients were lowest for fat yield. The most probable cause of overestimation in bull dam EBVs is preferential treatment, particularly in second and later lactations. To avoid this bias, estimation of a bull dam's breeding value should be based on pedigree information and on records from only her first lactation.     

Streptococcus equi subsp. zooepidemicus isolates from equine infectious endometritis belong to a distinct genetic group

Streptococcus equi subsp. zooepidemicus is the pathogen most commonly isolated from the uterus of mares. S. zooepidemicus is an opportunistic pathogen and part of the resident flora in the caudal reproductive tract. The aim of this study was to investigate whether a genotypically distinct subpopulation of S. zooepidemicus is associated with endometritis in the mare, by genotyping and comparing uterine S. zooepidemicus strains with isolates from the vagina and clitoral fossa. Mares with (n = 18) or without (n = 11) clinical symptoms of endometritis were included. Uterine samples were obtained using a guarded endometrial biopsy punch, whereas a swab was used to recover samples from the cranial vagina and the clitoral fossa. If S. zooepidemicus was present, up to three colonies were selected from each anatomical location (max. 9 isolates per mare). Bacterial isolates were characterized by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). S. zooepidemicus was isolated from the endometrium of 12 mares. A total of 88 isolates were analyzed by PFGE: 31 from the endometrium, 26 from the cranial vagina and 31 isolates from the clitoral fossa. For MLST 21 isolates were chosen. Results demonstrated a higher genetic similarity of the isolates obtained from infectious endometritis compared to isolates obtained from the caudal reproductive tract. In conclusion, we demonstrate for the first time that a genetically distinct group of S. zooepidemicus is associated with infectious endometritis in the mare.     

Comparison of hair follicle histology between horses with pituitary pars intermedia dysfunction and excessive hair growth and normal aged horses

Background –  Pituitary pars intermedia dysfunction (PPID) in older equids is commonly recognized by a long hair coat that fails to shed. Objective –  The aim of this study was to compare hair follicle stages in PPID‐affected horses with excessively long hair coats with the stages of normal aged horses (controls) and to compare hair follicle stages in PPID‐affected horses after 6 months of treatment with pergolide mesylate with those of control horses. Animals –  Eight PPID‐affected horses and four normal, age‐matched, control horses. Methods –  Skin biopsies were collected from the neck and rump of PPID‐affected and control horses. A diagnosis of PPID was established based on hair coat changes and supportive overnight dexamethasone suppression test results. Skin biopsies were repeated after 6 months of treatment with pergolide. The number of hair follicles in anagen (A) or telogen (T) was counted for each skin biopsy using transverse sections. Results –  Pretreatment biopsies had a greater percentage of A follicles (neck 96%, rump 95%) and a lower percentage of T follicles (neck 4%, rump 5%) in PPID‐affected horses than in control horses (A, neck 15%, rump 25%; and T, neck 85%, rump 75%). After treatment with pergolide, all PPID‐affected horses had improved shedding, and the percentages of A follicles (neck 69%, rump 70%) and T follicles (neck 31%, rump 30%) were not different from untreated control horses (A, neck 68%, rump 82%; and T, neck 32%, rump 18%). Conclusions –  These findings document that excessive hair growth (hypertrichosis) in PPID‐affected horses is due to persistence of hair follicles in A. Furthermore, treatment with pergolide improved shedding and reduced the percentage of A follicles in PPID‐affected horses.     

Spatio-temporal variation of anisotropy of saturated hydraulic conductivity in a tilled sandy loam soil

Knowledge on anisotropy of saturated hydraulic conductivity can improve the understanding of transport phenomena in soil. We hypothesized that saturated hydraulic conductivity (K_s) in the upper part of the root zone of an agricultural sandy loam soil was anisotropic at different soil depths and times after tillage. K_s was measured on undisturbed 100 cm³ core samples taken in the horizontal and vertical directions in up to four soil layers (Surf: surface layer (0–5 cm); Top: topsoil (10–15 cm); Trans: transition layer between topsoil and subsoil; Sub: subsoil (40–60 cm)) 1, 8 and 32 months, respectively, after mouldboard ploughing and drilling. The ratio between estimated geometric mean values for K_s in the vertical and the horizontal directions (K_ms,v/K_ms,h) was used to test the hypotheses. A total of 669 soil samples were analysed.K_ms,v/K_ms,h varied with time after tillage and between soil layers. One month after ploughing, K_ms,v/K_ms,h was <0.23 (P = 0.975) in the Trans layer with an average value of 0.084, i.e. K_ms,h was 12 times larger than K_ms,v. Anisotropy could not be documented in this layer 8 or 32 months after ploughing, i.e. K_ms,v/K_ms,h was not significantly different from 1.0. For the Surf and Top layers 32 months after ploughing, K_ms,v/K_ms,h was in the intervals 1.4–50 and 3.1–77, respectively, (P = 0.95) with average values of 8.4 and 15, respectively. Thus, K_ms,v was 8.4 respectively 15 times larger than K_ms,h in the two layers. Anisotropy was not found in these layers 1 or 8 months after tillage. Strong anisotropy was found in the Sub layer with K_ms,v/K_ms,h averaging to 14 and 32, respectively, 8 and 32 months after tillage. K_ms,v and K_ms,h generally decreased with time in the Surf, Top and Trans layers, except in the vertical direction in the Top layer between 8 and 32 months after ploughing, and in the Trans layer between 1 and 8 months after ploughing. Overall, the geometric means of K_s varied between 10^−4.0 and 10^−7.1 m s⁻¹.The results may reflect systematic effects of soil settlement and drying/wetting phenomena coupled with biological activity and the existence of stable, vertically oriented biopores in the subsoil. It appears to be necessary to consider anisotropy of K_s and its variation in the analysis and modelling of water flow and chemical transport in agricultural soils, particularly to explain heterogeneous flow phenomena at the plot and field scales.     

Linking watershed and microhabitat characteristics: effects on production of Atlantic salmonids (Salmo salar and Salmo trutta)

The spatial scale of environmental factors influencing population dynamics ranges from microhabitat to continental or even global scales. Integration of multiple spatial scales is important in order to understand links between environmental variation and population processes. In the present study, we investigate how multiscale drivers influence the production of stream‐rearing Atlantic salmonids (Atlantic salmon, Salmo salar L. and brown trout, Salmo trutta L.) measured in terms of abundance. Variation in juvenile production was studied using data from single‐pass electrofishing surveys (measured as biomass per m²) from nine rivers. These data were combined with habitat data ranging from an important in‐stream microhabitat variable (shelter availability) to properties of the catchment. Variation in productivity within and among rivers was affected by both properties of in‐stream habitat and catchment properties. Shelter availability and the proportion of the catchment consisting of cultivated land and lakes influenced biomass positively, while catchment area had the opposite effect. For a different set of rivers (N = 20), river gradient and catchment area were shown to positively affect the amount of shelter. Finally, the variables identified in the two preceding analysis were included in the analysis of population productivity using catch statistics from 160 rivers. The proportion of cultivated land and lakes, estimated shelter availability were found to have positive effects. In addition, temperature had a positive effect, while river width had a negative effect. This study shows that combining multiple‐scale environmental factors can explain a substantial proportion of variation in population productivity among and within the populations of Atlantic salmonids.     

Effects of Diet and Weight Gain on Body Condition Scoring in Thoroughbred Geldings

In the horse, the body condition score (BCS) system to assess subcutaneous fat deposition is a useful tool for making feeding management decisions. The system includes assessing fat deposition at six body areas (neck, withers, shoulders, ribs, loin, and tail head) and was developed in Quarter Horse mares. It has not been tested for use on other breeds or genders, possibly compromising the system's ability to describe fat accretion in other classes of horse. The objective of this study was to examine the ability of the previously developed fat accretion characteristics to describe fat deposition in mature Thoroughbred (TB) geldings. An additional goal was to determine whether fewer body areas could be used. Fifteen mature TB geldings were fed for weight gain over an 8-month period on one of two diets and were independently assessed for BCS on a monthly basis by two judges. BCS was determined by averaging the scores that were assigned to each of the six body areas. Fat accretion characteristics were also recorded. Across both diets, the neck area scored significantly higher than the withers and loin (P < 0.05) throughout the study. A BCS derived only from the body areas of neck, shoulders, ribs, and tailhead was found to accurately predict the six body area−derived mean BCS. The results of this study provide justification for modifications of the BCS system for use in TB geldings and also demonstrated that fewer body areas can be used to accurately predict mean BCS.     

Disseminated Leishmania infantum infection in two sibling foxhounds due to possible vertical transmission

Two sibling foxhounds born to a Leishmania seropositive bitch were presented after testing seropositive for Leishmania. Leishmania infantum infection was detected via histopathology, culture, and quantitative polymerase chain reaction (q-PCR). This is the first report of natural infection with Leishmania infantum with the possibility for vertical transmission in North America.     

Towards a risk-based surveillance for Trichinella spp. in Danish pig production

Increasing demands for cost-effectiveness in surveillance for human health hazards from animal origins can be met by introducing risk-based principles. This e.g. implies targeting subpopulations with higher risk of infection compared to the whole population. Furthermore, historical data from surveillance can be collated and used to assess future risk of infection. To demonstrate the effectiveness of combining these two approaches, we used a model called “Discounting historical evidence”. It depends mainly on the annual risk of introduction (PIntro) and the surveillance system sensitivity (SSe) (ability to detect infection if present). The model implies simulations that reiterate for a number of years. For each year the output is updated with the confidence on absence in infection. Trichinella spiralis infection in pigs is used as an example. In Denmark, more than 20 million pigs are tested annually. Despite more than 70 years of testing no pigs have been found positive for Trichinella. Hence, PIntro is low. SSe can be estimated from the maximum number of infected carcasses expected under the specified design prevalence, and the sensitivity of the test applied. According to our assessment, the current prevalence of Trichinella in Danish pigs is less than one case per million, which we interpret as negligible risk. Based on this, a risk-based surveillance programme for Trichinella is designed that targets all out-door reared pigs as well as all sows and boars (current total 610,000 slaughtered annually). These subpopulations are judged to have higher risk of getting Trichinella. Again, SSe and PIntro are estimated and the model results show that risk-based surveillance can be applied without jeopardizing human health. Finally, we incorporate wildlife surveys and test quality assurance in the programme. The results of the simulation model were included in an application to the European Commission concerning Denmark's status as a region with negligible risk of Trichinella. In July 2007, the European Commission granted status as “negligible risk” to Danish pigs and pork.