Monitoring training response in young Friesian dressage horses using two different standardised exercise tests (SETs)

Most Friesian horses reach their anaerobic threshold during a standardized exercise test (SET) which requires lower intensity exercise than daily routine training.to study strengths and weaknesses of an alternative SET-protocol. Two different SETs (SETA and SETB) were applied during a 2 month training period of 9 young Friesian dressage horses. SETB alternated short episodes of canter with trot and walk, lacking long episodes of cantering, as applied in SETA. Following parameters were monitored: blood lactic acid (BLA) after cantering, average heart rate (HR) in trot and maximum HR in canter. HR and BLA of SETA and SETB were analyzed using a paired two-sided T-test and Spearman Correlation-coefficient (p* < 0.05).BLA after cantering was significantly higher in SETA compared to SETB and maximum HR in canter was significantly higher in SETA compared to SETB. The majority of horses showed a significant training response based upon longitudinal follow-up of BLA. Horses with the lowest fitness at start, displayed the largest training response. BLA was significantly lower in week 8 compared to week 0, in both SETA and SETB. A significantly decreased BLA level after cantering was noticeable in week 6 in SETA, whereas in SETB only as of week 8. In SETA a very strong correlation for BLA and average HR at trot was found throughout the entire training period, not for canter.Young Friesian horses do reach their anaerobic threshold during a SET which requires lower intensity than daily routine training. Therefore close monitoring throughout training is warranted. Longitudinal follow up of BLA and not of HR is suitable to assess training response. In the current study, horses that started with the lowest fitness level, showed the largest training response. During training monitoring HR in trot rather than in canter is advised. SETB is best suited as a template for daily training in the aerobic window.Cornelis Marinus de Bruijn, Willem Houterman, Margreet Ploeg, Bart Ducro, Berit Boshuizen, Klaartje Goethals, Elisabeth-Lidwien Verdegaal and Catherine Delesall

Genetic parameters for social effects on survival in cannibalistic layers: Combining survival analysis and a linear animal model

<p>Abstract</p> <p>Background</p> <p>Mortality due to cannibalism in laying hens is a difficult trait to improve genetically, because censoring is high (animals still alive at the end of the testing period) and it may depend on both the individual itself and the behaviour of its group members, so-called associative effects (social interactions). To analyse survival data, survival analysis can be used. However, it is not possible to include associative effects in the current software for survival analysis. A solution could be to combine survival analysis and a linear animal model including associative effects. This paper presents a two-step approach (2STEP), combining survival analysis and a linear animal model including associative effects (LAM).</p> <p>Methods</p> <p>Data of three purebred White Leghorn layer lines from Institut de Sélection Animale B.V., a Hendrix Genetics company, were used in this study. For the statistical analysis, survival data on 16,780 hens kept in four-bird cages with intact beaks were used. Genetic parameters for direct and associative effects on survival time were estimated using 2STEP. Cross validation was used to compare 2STEP with LAM. LAM was applied directly to estimate genetic parameters for social effects on observed survival days.</p> <p>Results</p> <p>Using 2STEP, total heritable variance, including both direct and associative genetic effects, expressed as the proportion of phenotypic variance, ranged from 32% to 64%. These results were substantially larger than when using LAM. However, cross validation showed that 2STEP gave approximately the same survival curves and rank correlations as LAM. Furthermore, cross validation showed that selection based on both direct and associative genetic effects, using either 2STEP or LAM, gave the best prediction of survival time.</p> <p>Conclusion</p> <p>It can be concluded that 2STEP can be used to estimate genetic parameters for direct and associative effects on survival time in laying hens. Using 2STEP increased the heritable variance in survival time. Cross validation showed that social genetic effects contribute to a large difference in survival days between two extreme groups. Genetic selection targeting both direct and associative effects is expected to reduce mortality due to cannibalism in laying hens.</p

Genetic Analyses of Sow Longevity Traits, Age at First Farrowing and First-Litter Characteristics

Sow longevity is a vital trait in the pig production sector because of its economic and welfare importance. However, this trait is recorded late in a sow’s life and early selection criteria associated with sow longevity are beneficial for genetic improvement of sow longevity. The aim of this study was to estimate genetic parameters of sow longevity and other sow reproduction traits. Data included 14,284 purebred sows recorded from 1996 to 2016 in 7 commercial herds across Australia. Traits describing sow longevity included the number of maximum parities reached, length of productive lifetime in days, total number of piglets born alive per sow over her lifetime, and stayability from parity 1 to parity 4. Further traits considered were number of piglets born alive (litter size) and average piglet birth weight (both recorded in the first litter), and age at first farrowing. Sow longevity traits were genetically the same traits and had low heritabilities (0.07 to 0.13). Genetic correlations were lowly negative between sow longevity and age at first farrowing (-0.13 to -0.22), and between sow longevity and average piglet birth weight (-0.19 to -0.26). First litter size had positive genetic correlations with sow longevity traits (0.49 to 0.65). This study showed favourable genetic correlations of the traits first litter size and age at first farrowing with sow longevity, suggesting that these two traits could be suitable genetic indicators for sow longevity

Predicting Slaughter Weight in Pigs with Regression Tree Ensembles

Domestic pigs vary in the age at which they reach slaughter weight even under the controlled conditions of modern pig farming. Early and accurate estimates of when a pig will reach slaughter weight can lead to logistic efficiency in farms. In this study, we compare four methods in predicting the age at which a pig reaches slaughter weight (120 kg). Namely, we compare the following regression tree-based ensemble methods: random forest (RF), extremely randomized trees (ET), gradient boosted machines (GBM), and XGBoost. Data from 32979 pigs is used, comprising a combination of phenotypic features and estimated breeding values (EBV). We found that the boosting ensemble methods, GBM and XGBoost, achieve lower prediction errors than the parallel ensembles methods, RF and ET. On the other hand, RF and ET have fewer parameters to tune, and perform adequately well with default parameter settings.</p

Possible negative effects of inbreeding on semen quality in Shetland pony stallions

Inbreeding is widely believed to negatively affect reproductive performance. Indeed, in some species, high levels of inbreeding are thought to be the major cause of poor semen quality. It is, however, not clear whether inbreeding affects fertility in horses. In this study, the relationship between inbreeding and semen quality was examined in 285 immature Shetland pony stallions submitted for breeding soundness examination in March-April of the years 1992-1997. The majority of stallions examined were 3 years old (85%) and their coefficients of inbreeding ranged from 0 to 25% (mean ± S.D.: 3 ± 4.6%). For the purpose of analysis, stallions were divided into six inbreeding classes (0-1, 1-2, 2-5, 5-8, 8-12 and >12%) containing 132, 40, 42, 27, 25 and 19 animals, respectively. The degree of inbreeding significantly affected many aspects of sperm production and quality, based on a standard examination of two ejaculates collected at a 1.5-3 h interval. In particular, coefficients of inbreeding above 2% were associated with lower percentages of motile (p <0.01) and morphologically normal sperm (p <0.001). When the data set was used to estimate heritability of semen characteristics, the high values calculated for sperm progressive motility (0.46) and concentration (0.24) suggested that these traits could be improved by phenotypic selection. These findings support the hypothesis that inbreeding has a detrimental effect on semen quality in Shetland ponies, although examination of multiple ejaculates after repeated semen collection to bring the animals to daily sperm output is needed to confirm this conclusion. Nevertheless, the results support previous suggestions that inbreeding is an important cause of reduced semen qualit

Development, DNA fragmentation and cell death in porcine embryos afer 24 h storage under different conditions

For practical applications of porcine embryo transfer (ET) it is important to develop feasible embryo storage conditions. The aim of the present study was to evaluate the effect of short-term storage (24 h) on the quality of in vivo produced porcine embryos. Three temperatures 18, 25 and 38 degreesC and three different media: Dulbecco's phosphate buffered saline (DPBS), TCM199 and Emcare(R) were tested for two different embryo ages: D4 embryos (collected 144 h after hCG treatment) and D5 embryos (collected 168 h after hCG). After slaughter of the donor gilts, embryos were collected and transported at 25 degreesC to the lab where morulas and blastocyst were selected (D4 n = 222; D5 n = 167) and randomly used as controls or distributed over the treatment groups. Developmental stage and embryo diameter were assessed by normal light microscopy, while total number of cells and incidence of apoptosis were assessed using a fluorescent embryo quality staining technique that combines three different dyes: Ethidium Homodimer (EthD-1), TUNEL and Hoechst 33342. Following 24 h storage, D5 embryos had higher rates of hatching (24%) and degeneration (9%) compared to D4 embryos (10 and 4%, respectively; P <0.05). Embryos stored at 38 &DEG;C had higher rates of hatching (37%) compared to those ones stored at 25 &DEG;C (13%) or 18 T (0%; P <0.01). More embryos hatched when stored in medium Dulbecco's phosphate buffered saline (DPBS) or in TCM199 compared to those stored in Emcare (P <0.05). A higher percentage of embryos stored at 18 &DEG;C degenerated compared to those stored at 25 or 38 &DEG;C (P <0.01). No significant increase in apoptosis was observed after storage compared to the rates of apoptosis at 0 h (controls) or between the different storage groups. Based on the results we conclude that D4 porcine embryos produced in vivo, selected under normal light microscopy and stored at 25 degreesC in a serum free medium for 24 h will have a suitable developmental stage for ET and a high embryo quality. (C) 2003 Elsevier Inc. All rights reserved

The effects of dry period length and dietary energy source on natural antibody titers and mammary health in dairy cows

In earlier studies, natural antibodies (NAb) were related not only to the energy balance (EB) of dairy cows, but also to somatic cell count (SCC) and clinical mastitis (CM). The first objective of our study was to evaluate the effects of dry period length and dietary energy source on titers of NAb binding keyhole limpet hemocyanin (KLH) and lipopolysaccharide (LPS) in plasma and milk, SCC and CM occurrence in dairy cows in two subsequent lactations. Our second objective was to study the relationship between NAb levels and mammary health. Holstein-Friesian dairy cows (N = 167) were randomly assigned to three dry period lengths (0, 30 or 60-d) and two early lactation rations (glucogenic or lipogenic). Treatments were repeated during two subsequent lactations (years 1 and 2). In year 2, 19 cows which were planned to have 0-d dry period dried off naturally and were assigned to an additional group 0 → 30-d dry period. In year 1, cows with a 0-d dry period had a higher SCC, a higher titer of immunoglobulin G (IgG) binding LPS in plasma, and higher titers of IgG and IgM binding KLH and LPS in milk compared with cows with a 30-d or 60-d dry period. In year 2, cows with a 60-d dry period had a lower SCC than cows with a 30-d and 0 → 30-d dry periods. In year 2, dry period length did not affect NAb titers in plasma or milk. The CM occurrence was 17 percent in year 1 of the experiment and 25 percent in year 2, and did not differ according to dry period lengths or rations. For both years, an increasing titer of IgG binding LPS in plasma was associated with decreased odds of a high SCC and decreased odds of CM occurrence. Also up to three weeks before the CM occurrence, an increasing titer of IgM binding KLH and LPS in plasma was associated with a decreased odds of CM occurrence. In conclusion, omitting the dry period increased SCC, NAb titers in milk and IgG binding LPS in plasma compared with a short (30-d) or conventional (60-d) dry period. The effects on NAb titers, however, were only present in the first year after omitting the dry period and disappeared after repeated omitting the dry period. Moreover, an increasing titer of IgG binding LPS in plasma was associated with decreased odds of high SCC and CM occurrence

Short-term feeding strategies and pork quality

Two experiments were done to determine whether short-term supplementation (5 days pre-slaughter) with magnesium acetate, or a combination of magnesium acetate, tryptophan, vitamin E and vitamin C would improve pork quality. In the first experiment the pigs (Pietrain x Yorkshire, n = 96) were fed a standard feed or a magnesium supplemented feed for 5 days prior to slaughter. As a possible stress factor half of the animals were slaughtered upon arrival at the slaughterplant whereas the remaining animals were allowed two hours of rest in lairage before slaughter. Magnesium supplementation did not result in an increase in plasma magnesium concentration at slaughter. Omission of lairage resulted in higher plasma glucose concentrations, but plasma lactate concentrations were not affected. Drip loss and ultimate pH were not affected by diet or omission of lairage. Omission of lairage resulted in poorer color characteristics. This effect was prevented by supplementation with magnesium. In the second experiment the pigs (Pietrain x Yorkshire, n = 92) were fed a standard feed or this standard feed supplemented with magnesium acetate, tryptophan, vitamin E and vitamin C for 5 days prior to slaughter. Supplementation with vitamin E did not increase muscle vitamin E concentration. Inclusion of supplements in the diet failed to improve water-holding capacity or color characteristics. These results indicate that short-term supplementation with magnesium acetate, tryptophan, vitamin E and vitamin C is of little value in improving pork quality when pigs are not stressed beyond levels associated with routine slaughter procedures. (C) 2003 Elsevier Ltd. All rights reserved