Genetic parameters for the prediction of abdominal fat traits using blood biochemical indicators in broilers

1. Excessive deposition of body fat, especially abdominal fat, is detrimental in chickens and the prevention of excessive fat accumulation is an important problem. The aim of this study was to identify blood biochemical indicators that could be used as criteria to select lean Yellow-feathered chicken lines.

2. Levels of blood biochemical indicators in the fed and fasted states and the abdominal fat traits were measured in 332 Guangxi Yellow chickens. In the fed state, the genetic correlations (r_g) of triglycerides and very low density lipoprotein levels were positive for the abdominal fat traits (0.47 ≤ r_g ≤ 0.67), whereas total cholesterol, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) showed higher negative correlations with abdominal fat traits (–0.59 ≤ r_g ≤ ?0.33). Heritabilities of these blood biochemical parameters were high, varying from 0.26 to 0.60.

3. In the fasted state, HDL-C:LDL-C level was positively correlated with abdominal fat traits (0.35 ≤ r_g ≤ 0.38), but triglycerides, total cholesterol, HDL-C, LDL-C, total protein, albumin, aspartate transaminase, uric acid and creatinine levels were negatively correlated with abdominal fat traits (–0.79 ≤ r_g ≤ ?0.35). The heritabilities of these 10 blood biochemical parameters were high (0.22 ≤ h² ≤ 0.59).

4. In the fed state, optimal multiple regression models were constructed to predict abdominal fat traits by using triglycerides and LDL-C. In the fasted state, triglycerides, total cholesterol, HDL-C, LDL-C, total protein, albumin and uric acid could be used to predict abdominal fat content.

5. It was concluded that these models in both nutritional states could be used to predict abdominal fat content in Guangxi Yellow broiler chickens.     

Genetic Relations between Reproduction,Chick Weight and Maternal Egg Composition in a White Leghorn Line

Selection is a viable way to increase egg dry matter, an important trait for the egg processing industry, but simultaneously a change in the embryonic environment takes place. The main purpose of this study was to estimate genetic parameters for the percentage of fertile eggs of eggs set (FERT), percentage of eggs hatched of fertile eggs (HATCH), percentage of live chicks 2 weeks post-hatch of hatched eggs (SURV/h) and of fertile eggs (SURV), and their genetic correlations with egg weight, albumen weight, yolk weight, yolk proportion, albumen dry matter and mean chick weight in a White Leghorn selection line. Direct and maternal heritabilities were low for FERT, HATCH and SURV, and non-existent for SURV/h. All direct-direct genetic correlations between reproduction traits and egg composition traits were not significant. Maternal-direct genetic correlations between HATCH and egg weight, albumen weight, yolk weight, yolk proportion and albumen dry matter were - 0.22, - 0.30, 0.28, 0.52 and 0.26, respectively. Similar correlations were found between SURV and egg composition traits. No significant genetic relationship was found between chick weight and post-hatch survival. In conclusion, within the range of values for egg composition in this study, selection for an increased egg dry matter should not impair reproduction.     

Effect of starting body fat content and genotype of laying hens on the changes in their live weight,body fat content,egg production and egg composition during the first egg-laying period

1. A total 120 laying hens (60 TETRA BLANCA white egg layers and 60 TETRA SL brown egg layers) were selected from 250 TETRA BLANCA and 250 TETRA SL pullets based on their predicted body fat content by means of computed tomography (CT) at 16 weeks of age. Three groups of pullets were chosen for the investigation with the highest (n = 20), lowest (n = 20) and average (n = 20) body fat content.

2. Changes in the live weight, body fat content, egg production and egg composition of the chosen animals were recorded at 32, 52 and 72 weeks of age.

3. Based on the results, it was established that differences in starting body fat content of the hens remained the same during the experimental period. The differences between the two extreme groups were statistically significant at each age.

4. The starting body fat content of the hens affected the rate of egg production, i.e. hens with high starting body fat content produced 11–14 eggs fewer than the hens with a low or average body fat content but had no effect on the composition of the eggs.

5. Genotype affected almost all of the examined traits: TETRA BLANCA hens had lower live weight and higher body fat content during the experimental period and produced fewer eggs with lower albumen and higher yolk, dry matter and crude fat content than the TETRA SL hens.

     

Estimates of genetic parameters for milkability from automatic milking

Genetic parameters were estimated by restricted maximum likelihood with a multi-trait animal model for three milkability traits with serial data from an automatic milking system from a research farm (401 dairy cows) collected between September 2000 and June 2003 (320834 milkings). Furthermore, daily values for milk yield and milkability were formed from all single milkings resulting in 104 132 records and, subsequently, an estimation of genetic parameters was carried out based on these daily values.The resulting estimated heritability coefficients (based on daily values) are h² = 0.55, h² = 0.55 and h² = 0.39 for average milk flow, maximum milk flow and milking time, respectively. The heritabilities are at a high level and thus breeding for good milkability makes sense. The genetic correlations between the three milkability traits are near unity with r_g = 0.98 between average and maximum milk flow, r_g = − 0.89 between average milk flow and milking time and r_g = − 0.86 between maximum milk flow and milking time. Thus it may be sufficient to record only one of these traits in performance tests. The genetic correlations between milk yield and average milk flow, maximum milk flow and milking time are r_g = 0.51, r_g = 0.44 and r_g = − 0.23, respectively.In future, serial data on milkability, already existing on many farms with automatic milk yield recording, should be used to greater extent for selective breeding with the aim of achieving good milkability.     

Multivariate genetic analysis to account for preselection and disqualified races in the genetic evaluation of racing performances in German trotters

Abstract

The genetic associations between racing performance and preselection of horses considered as the binary trait racing status (trotters without or with at least one racing performance in life were classified as 0 and 1, respectively) as well as disqualified races (disqualified and non-disqualified trotters were classified as 1 and 0, respectively) were analysed in German trotters. Variance components for racing performance traits square root of rank at finish, racing time per km, and log of earnings with racing status were estimated based on an animal model using REML. Heritabilities of racing status, racing time and rank at finish were 0.30, 0.21, and 0.06, respectively. The genetic correlations between racing status and racing time or rank at finish were ?0.74 and ?0.32, indicating that horses started at least once showed a higher genetic potential in racing time or finishing ability than never started horses. This showed the high preselection of German trotters especially based on racing time. To account for this preselection, it was recommended for additional use of racing status in the German evaluation system. Breeding values of the three racing performance traits were estimated by two distinct models, in- or excluding racing status and compared by using three criteria. Racing time per km showed the highest correlation (r=0.98) between breeding values evaluated by these two distinct models. Therefore, incorrect selection rate of horses using breeding values from the model without racing status, was lowest for racing time per km (9.7%). Selection response increased about 1% for this trait after including racing status in the model. For the estimation of rank at finish, inclusion of racing status in the multiple trait model was much more important as indicated by a low correlation between breeding values (r=0.29) and high percentage of incorrectly selected stallions (97.5%). The trait disqualified races was first analysed using an univariate threshold model. Heritability of this trait was low (h ²=0.12) and repeatability (r=0.43) showed a moderate magnitude. Using a linear multiple trait animal model, disqualified races showed a low heritability (h ²=0.05) and a moderate favourable genetic correlation (r _g=0.43) with racing time per km. Consequently, selection on racing time per km is expected to improve indirectly the reliability of racing performance. Combined selection of reduction in disqualified races and racing time may even further improve the reliability of racing trotters.     

Genetic variation of in vivo muscle glycerol,glycogen, and pigment in Danish purebred pigs

Heritability values of glycerol, glycogen and pigment concentrations measured on muscle biopsy samples from longissimus dorsi obtained from 85?kg boars of Danish purebred pigs (Landrace, Yorkshire, and Duroc) and their genetic correlations to performance and meat quality traits were calculated. The heritability values of glycogen, pigment, and glycerol were 0.38±0.02, 0.17±0.02, and 0.065±0.016, respectively. Glycogen was negatively related to the feed conversion ratio (FCR) (r _g =?0.25±0.06) and ultimate meat pH (r _g =?0.41±0.04), and positively to the carcass meat percentage (r _g =0.35±0.04), L* (lightness of meat, r _g =0.32±0.04) and a* (redness of meat, r _g =0.12±0.03). Pigment was positively related to the FCR (r _g =0.12±0.05), the meat percentage (r _g =0.28±0.05), and a* (r _g =0.59±0.04), and negatively to the L* (r _g =?0.46±0.06). The concentrations of pigment and glycogen (r _g =0.27±0.05) were interrelated. Based on the heritability values and the signs of the genetic correlations the present data suggest that it is possible to select for higher ultimate pH and improved colour by selection for either lower muscle glycogen or higher pigment concentration, respectively. However, the positive genetic correlation between these two traits may restrict the efficiency of simultaneous selection for lower glycogen and higher pigment. All genetic parameter estimates presented are calculated across three purebreds. Values for each breed are warranted for use in pig production. However, this requires more animals per breed.     

Improving production efficiency in the presence of genotype by environment interactions in pig genomic selection breeding programmes

We simulated a genomic selection pig breeding schemes containing nucleus and production herds to improve feed efficiency of production pigs that were cross‐breed. Elite nucleus herds had access to high‐quality feed, and production herds were fed low‐quality feed. Feed efficiency in the nucleus herds had a heritability of 0.3 and 0.25 in the production herds. It was assumed the genetic relationships between feed efficiency in the nucleus and production were low (r_g = 0.2), medium (r_g = 0.5) and high (r_g = 0.8). In our alternative breeding schemes, different proportion of production animals were recorded for feed efficiency and genotyped with high‐density panel of genetic markers. Genomic breeding value of the selection candidates for feed efficiency was estimated based on three different approaches. In one approach, genomic breeding value was estimated including nucleus animals in the reference population. In the second approach, the reference population was containing a mixture of nucleus and production animals. In the third approach, the reference population was only consisting of production herds. Using a mixture reference population, we generated 40–115% more genetic gain in the production environment as compared to only using nucleus reference population that were fed high‐quality feed sources when the production animals were offspring of the nucleus animals. When the production animals were grand offspring of the nucleus animals, 43–104% more genetic gain was generated. Similarly, a higher genetic gain generated in the production environment when mixed reference population was used as compared to only using production animals. This was up to 19 and 14% when the production animals were offspring and grand offspring of nucleus animals, respectively. Therefore, in genomic selection pig breeding programmes, feed efficiency traits could be improved by properly designing the reference population.     

Effect of feeding broccoli floret residues on leghorn layer performance and egg quality and nutrient digestibility

1. A study was conducted to determine the effects of dried broccoli floret (DBF) on egg production parameters, egg quality and apparent nutrient digestibility of laying hens. It was hypothesised that feeding DBF can improve egg quality without adversely affecting layer performance.2. Seventy-two White Leghorn layers aged 62 weeks were randomly allotted to 4 dietary treatments (6 cage replicates with 3 hens each) and fed diets containing 0, 40, 80 and 120 g/kg DBF in feed for 56 d.3. Inclusion of DBF had no effect on feed intake, egg production, feed conversion ratio or egg components. However, egg weight increased (linear effect, P < 0.05) as the level of DBF in the diet increased. Egg breakage strength, eggshell strength and Haugh unit were not influenced by dietary treatments. Egg yolk colour (quadratic effect, P = 0.002) and α-tocopherol concentration (quadratic effect, P < 0.0001) improved as a result of DBF inclusion. Egg yolk cholesterol concentration was not altered by DBF inclusion. Apparent total tract nutrient (dry matter, organic matter and crude protein) digestibility coefficients decreased (linear effect, P < 0.05) as the level of DBF increased.4. Feeding DBF to layers up to 120 g/kg of the diet had no negative effects on feed intake, egg production and feed efficiency and improved egg yolk colour and α-tocopherol concentration. However, total tract nutrient digestibility coefficients were negatively decreased as a result of DBF inclusion.     

Estimates of phenotypic and genetic parameters for birth weight of Brown Swiss calves in Turkey using an animal model

A study was conducted to assess the influence of genetic and environmental factors on Brown Swiss calf birth weight, and to estimate variance components, genetic parameters, and breeding values. Data were collected on 1,761 Brown Swiss calves born from 1990 to 2005 in the Konuklar State Farm in Turkey. Mean birth weight for all calves was 39.3 ± 0.09 kg. Least squares mean birth weights for male and female Brown Swiss calves were 40.3 ± 0.02 and 39.0 ± 0.02 kg, respectively. Variance components, genetic parameters, and breeding values for birth weight in Brown Swiss calves were estimated by restricted error maximum likelihood (REML)–best linear unbiased prediction(BLUP) procedures using an MTDFREML (multiple trait derivative free restricted maximum likelihood) program employing an animal model. Direct heritability (h _d²), maternal heritability (h _m²), total heritability (h _T²), r _am and c _am estimates were 0.12, 0.09, 0.23, −0.58, and −0.06, respectively. The estimated maternal permanent environmental variance expressed as a proportion of the phenotypic variance (c ²) was 0.05. Breeding values were estimated for the trait and used to evaluate genetic trends across the time period investigated. The genetic trend linear regression was not different from zero. No genetic trend for birth weight was expected, since there had been no direct selection pressure on the trait. Absence of a trend confirms that there was no change due to selection pressure on correlated traits. Genetic and environmental parameter estimates were similar to literature values indicating that effective selection methods used in more developed improvement programs would be effective in Turkey as well.     

Genetic variation for worm burdens in laying hens naturally infected with gastro-intestinal nematodes

1. Genetic parameters were determined for the worm burden of the most common gastro-intestinal nematodes in two chicken genotypes after being exposed to free-range farming conditions for a laying period.

2. Seventeen-week-old hens of 2 brown genotypes, Lohmann Brown (LB) plus (n = 230) and LB classic (n = 230), were reared for a laying period and subjected to post-mortem parasitological examinations at 79 weeks (LB plus) or 88 weeks (LB classic) of age.

3. There was no significant difference in faecal egg counts between the genotypes. Almost all hens (>99%) were infected with at least one nematode species. Species-specific nematode prevalence ranged from 85.8% to 99.1% between the two genotypes. Heterakis gallinarum was the most prevalent nematode (98.5%), followed by Ascaridia galli (96.2%) and Capillaria spp. (86.1%). Capillaria spp. were composed of C. obsignata (79%), C. caudinflata (16%) and C. bursata (5%).

4. All phenotypic and genetic correlations among worm counts of different parasite species were positive in combined genotypes (r_P ranged from 0.05 to 0.30 and r_G ranged from 0.29 to 0.88). A strong genetic correlation (r_G = 0.88 ± 0.34) between counts of A. galli and H. gallinarum was quantified. Heritability for total worm burden for LB plus and LB classic, respectively, were 0.55 ± 0.18 and 0.55 ± 0.34. Across both genotypes, the heritability of total worm burden was 0.56 ± 0.16.

5. In conclusion, there is a high variation attributable to genetic background of chickens in their responses to naturally acquired nematode infections. The high positive genetic correlation between counts of closely related worm species (e.g. A. galli and H. gallinarum) may indicate existence of similar genetically determined mechanism(s) in chickens for controlling these nematodes.

     

Physiological Predictors in Calves of Dairy Breeds: Part 1. Genetic Parameters of Basal and Induced Growth Hormone Secretion

Abstract

Genetic variation in plasma growth hormone (GH) concentration before and after GRF (growth hormone releasing factor) stimulation was studied in young bulls (N=284) and heifers (N=212), the progeny of 53 sires of four dairy and dual-purpose breeds (Danish Jersey, Red Dane, Danish Friesian and Danish Red and White). Male and female calves were reared, fed and tested on separate experimental stations; thus sex, station and feeding were completely confounded effects. The animals were tested at about 9 months of age, after a 24 h fast. GH concentration was measured in serial plasma samples collected for 1 h before and 1 h following intravenous administration of 2.0 ug synthetic GRF(1–29)NH₂/kg live weight^>0.75. Prior to statistical analysis, concentrations were log_e-transformed. Response variables were BASELINE (mean GH in -15, -5 and 0 min samples) and PEAK (mean GH in 10, 15 and 20 min samples). A statistical model taking at least three generations of ancestral relationships into account was used to estimate variance and covariance components for traits in male and female calves by use of restricted maximum likelihood methods.

Heritability of BASELINE was low (0.04 ± 0.12) in males but high in females (0.60 ± 0.16). The heritability of PEAK was high in both sexes (males, 0.42 ± 0.16; females, 0.60 ± 0.16). Genetic correlations between the same trait measured in males and females were low for BASELINE (r _g = 0.32±0.55) but high for PEAK (r _g = 0.82±0.15). Within sex, BASELINE and PEAK were both highly genetically correlated (males, r _g=0.62 ± 0.40; females, r _g= 1.00 ± 0.07).

We conclude that growth hormone concentration is a highly heritable trait in juvenile cattle of both sexes, and that GRF stimulation is benificial to the uncovering of genetic differences among animals.     

Heritability of clinical tail-biting and its relation to performance traits

Clinical tail-biters were identified over a 12-month period at a commercial nucleus pig-breeding farm that had a history of tail-biting problems. The breed, gender, and relative size of the tail-biters were recorded. Using pedigree data for all the pigs on the farm at the time of observations, the heritability of the tail-biting behaviour was estimated for purebred Large White (LW) and Landrace (LR) pigs. The incidence of tail-biting was 2.8% for Large White and 3.5% for Landrace (breed effects, P<0.10). Tail-biting was found to be heritable in Landrace (h²=0.05±0.02, P<0.05 as a 0-1 trait, equivalent to h²=0.27 as a continuous trait), but not heritable in Large White pigs (h²=0.00±0.00, as a 0-1 trait). In the Landrace population, tail-biting was unfavourably genetically correlated with leanness [lean tissue growth rate (LTGR; r_g=0.27, P<0.05), and back fat (BF) thickness at 90 kg (r_g=−0.28, P<0.05)]. It is concluded that past selection for desirable production traits may have resulted in increased predisposition to exhibit tail-biting behaviour. From the correlations and covariance matrix reported, it would be possible to develop a selection index to reduce the predisposition to exhibit tail-biting behaviour through selective breeding.     

Muscle fibre traits as additional selection criteria for muscle growth and meat quality in pigs – results of a simulated selection

To estimate the direct and correlated responses in meatiness and meat quality, simulated selection was applied using one‐trait selection and index selection including muscle fibre traits. In a total of 2024 pigs of German Landrace, Large White, Leicoma, and Schwerfurter breeds, carcass composition, meat quality, and fibre characteristics of the M. longissimus lumborum were analysed and genetic parameters were calculated by using REML variance component estimation. Coefficients of heritability ranged from low to moderate (growth traits: h² = 0.22–0.32; meat quality traits: h² = 0.17–0.27; muscle fibre traits: h² = 0.12–0.20). The total fibre number and the frequency of white fibres correlated positively with live weight (r_g = 0.44 and 0.44, respectively) and with loin muscle area (r_g = 0.38 and 0.19, respectively) while the relationships to pH value and drip loss were not as close (r_g = ?0.29–0.19). Selection indices were constructed from live weight and muscle area, from pH value and drip loss, and from muscle structure traits. As expected, simulated selection for live weight or loin muscle area lead to direct positive effects but these were associated with negative effects on meat quality traits (selection intensities: SI = 0.1; 0.5). Using selection for an index from loin area and muscle structure (loin muscle area + total fibre number – frequency of white fibres – frequency of giant fibres) the adverse effect on meat quality was minimized (responses in pH value: ?0.05; ?0.01) or was changed towards desired direction (responses in drip loss: ?0.65%; ?0.26%). The results show that fibre characteristics of pig muscle can be used as selection criteria for simultaneous improvement of carcass composition and meat quality in pigs by including indices developed from performance and fibre traits.     

Dominance genetic and maternal effects for genetic evaluation of egg production traits in dual-purpose chickens

• 1.?A study was conducted to study direct dominance genetic and maternal effects on genetic evaluation of production traits in dual-purpose chickens. The data set consisted of records of body weight and egg production of 49 749 Mazandaran fowls from 19 consecutive generations. Based on combinations of different random effects, including direct additive and dominance genetic and maternal additive genetic and environmental effects, 8 different models were compared.

• 2.?Inclusion of a maternal genetic effect in the models noticeably improved goodness of fit for all traits. Direct dominance genetic effect did not have noticeable effects on goodness of fit but simultaneous inclusion of both direct dominance and maternal additive genetic effects improved fitting criteria and accuracies of genetic parameter estimates for hatching body weight and egg production traits.

• 3.?Estimates of heritability (h²) for body weights at hatch, 8 weeks and 12 weeks of age (BW0, BW8 and BW12, respectively), age at sexual maturity (ASM), average egg weights at 28–32 weeks of laying period (AEW), egg number (EN) and egg production intensity (EI) were 0.08, 0.21, 0.22, 0.22, 0.21, 0.09 and 0.10, respectively. For BW0, BW8, BW12, ASM, AEW, EN and EI, proportion of dominance genetic to total phenotypic variance (d²) were 0.06, 0.08, 0.01, 0.06, 0.06, 0.08 and 0.07 and maternal heritability estimates (m²) were 0.05, 0.04, 0.03, 0.13, 0.21, 0.07 and 0.03, respectively. Negligible coefficients of maternal environmental effect (c²) from 0.01 to 0.08 were estimated for all traits, other than BW0, which had an estimate of 0.30.

• 4.?Breeding values (BVs) estimated for body weights at early ages (BW0 and BW8) were considerably affected by components of the models, but almost similar BVs were estimated by different models for higher age body weight (BW12) and egg production traits (ASM, AEW, EN and EI). Generally, it could be concluded that inclusion of maternal effects (both genetic and environmental) and, to a lesser extent, direct dominance genetic effect would improve the accuracy of genetic evaluation for early age body weights in dual-purpose chickens.

     

Effect of probiotics on enrofloxacin disposition in gastrointestinal tract of poultry

Probiotics are routinely used in poultry husbandry due to health benefit on the host. The gut microbiota is now recognized to exert an important influence on the absorption and pharmacokinetics of many compounds. Therefore, this study was designed to evaluate the effect of candidate probiotics belonging to the species Lactobacillus brevis, L. plantarum and L. bulgaricus on pharmacokinetics of enrofloxacin in healthy chickens. The probiotic administration leads to higher degree of metabolism of enrofloxacin to ciprofloxacin in liver. The antibacterial drug was significantly faster absorbed (k_ab of 0.61 ± 0.54 h^?1 and T_max 7.81 ± 3.52 h) at lower concentrations (C_max of 1.34 ± 0.18 μg·g^?1) during the first 24 h of treatment in the probiotic's group. The values of k_ab, T_max, and C_max for the group, treated solely with enrofloxacin, were 0.10 ± 0.065 h^?1, 15.42 ± 3.07 h, and 1.61 ± 0.24 μg·g^?1, respectively. A significantly higher concentration of enrofloxacin and its metabolite ciprofloxacin in the liver was observed in the group with the probiotic treatment. Disposition of both drugs was not significantly changed in the duodenum and in the jejunum. The selected dose is appropriate for treatment of infections caused by pathogens with MIC < 0.06 μg·mL^?1 irrespective of antibiotic administration alone or in combination with probiotics.     

Comparison of single- and multi-strain probiotics effects on broiler breeder performance,egg production,egg quality and hatchability

ABSTRACT

1. This study was conducted to investigate the effect of multi-strain probiotic (containing Lactobacillus acidophilus 2.5 × 10⁷ cfu/g, Lactobacillus casei 2.5 × 10⁷ cfu/g, Bifidobacterium thermophilum 2.5 × 10⁷ cfu/g and Enterococcus faecium 2.5 × 10⁷ cfu/g) and single-strain probiotic (Pediococcus acidilactici 1 × 10¹⁰ cfu/g) on broiler breeder performance and gastrointestinal health.

2. A completely randomised trial was conducted using 300 broiler breeder hens (Ross 308) aged 51 weeks old which were randomly allocated to 1 of 5 dietary treatments with 6 replicates per treatment in a 10 week trial. Treatments included (1) the basal diet a negative control, (2) basal diet supplemented with 0.1 g/kg multi-strain probiotic (MS), (3) basal diet supplemented with 0.1 g/kg single-strain probiotic (SS), (4) basal diet supplemented with 0.1 g/kg of both of probiotics (MS+ SS) and (5) positive control basal diet supplemented with 0.5 g/kg oxytetracycline antibiotic (OX).

3. Body weight, egg production, yolk weight, eggshell thickness and weight, Haugh unit, fertility and hatchability were determined. Results showed that dietary treatments had no significant effect on total hen house or total hatching egg production, egg weight, yolk colour index, shell weight, mortality, body weight, fertility, hatchability, oviduct and stroma weight or number of large and small yellow follicles (P > 0.05). None of the jejunum morphological parameters, apparent ileal digestibility of protein and ileal Lactobacillus population were influenced by supplemental probiotics (P > 0.05), although ileum Escherichia coli count was reduced by inclusion of dietary probiotics (P < 0.05).

4. It was concluded that although both probiotic treatments reduced coliforms, they did not improve broiler breeder performance or gastrointestinal tract (GIT) function.     

Estimation of genetic parameters for the prevalence of osseous fragments in limb joints of Hanoverian Warmblood horses

Genetic parameters were estimated for the prevalence of osseous fragments in distal (DIJ) and proximal interphalangeal (PIJ), fetlock (FJ) and hock joints (HJ) of Hanoverian Warmblood horses by using residual maximum likelihood (REML) with linear animal models. The analyses were based on the results of 10 standardized radiographs of all four limbs of 3725 young riding horses selected for sale at auction. Transformation factors onto the underlying liability scale were verified by a simulation study. The heritability estimates of osseous fragments on the liability scale were in the range of h² = 0.19–0.60. Further analyses of osseous fragments in FJ and HJ were performed separately in males and females. In both sexes, the heritabilities of osseous fragments in HJ were higher (h² = 0.41 in males, h² = 0.25 in females) than those of osseous fragments in FJ (h² = 0.21 in males, h² = 0.23 in females). Osseous fragments in the phalangeal joints (DIJ, PIJ, FJ) were genetically correlated moderately positive (r_g = 0.19–0.41). The genetic correlations between osseous fragments in the phalangeal joints and in HJ were negative (r_g = ?0.27 to ?0.67). Particularly, this applied to osseous fragments in FJ in both sexes, to those in front FJ in males and to osseous fragments in front and hind FJ of females (up to r_g = ?1). The heritability of height at withers was estimated at h² = 0.27–0.28. Genetic correlations between height at withers and osseous fragments in equine limb joints were mostly moderately positive (up to r_g = 0.75). We conclude from our results that osseous fragments in phalangeal and hock joints are genetically different traits but sex‐specific expression of osseous fragments was unlikely.     

Genetic variation and genetic trends in hip and elbow dysplasia in Swedish Rottweiler and Bernese Mountain Dog

The aim of this study was to estimate genetic parameters and genetic trends for hip (HD) and elbow dysplasia (ED) in Swedish Rottweiler (RW) and Bernese Mountain Dog (BMD). Analyses were based on screening results of hip status for 14 693 RW and 8221 BMD and elbow status for 11 891 RW and 7963 BMD, as well as pedigree data for 16 614 RW and 9835 BMD, recorded by the Swedish Kennel Club. Components of (co)variance and breeding values were obtained with a mixed linear animal model. The model included the fixed effects of sex, birth month, age at screening and a combined random effect of clinic and year of examination. The need to include genetic groups for phantom parents in the model was evaluated by comparison of two different models: with and without genetic groups. Estimated heritabilities for HD and ED were between 0.34 and 0.42. The genetic correlation between the traits was weak and positive for RW (r_g = 0.23 ± 0.05) and not different from zero for BMD (r_g = 0.06 ± 0.06). F‐statistics of the genetic group effects were not significant, implying that genetic groups do not need to be included in the model. Genetic trends indicated a genetic improvement in both traits. However, a faster genetic progress is expected if selection is based on predicted breeding values rather than phenotype. Based on the results, a statistical model for routine prediction of breeding values for HD and ED in Swedish dogs was suggested.     

Anaylse von Spermaqualitätsformationen aus dem Zuchtprogramm des Angler Rindes

Inhalt: In der vorliegenden Arbeit wurden Spemtaqualitätsinformationen aus dem Zuchtprograrnm des Verbandes der Angler Rinderzüchter e.V., Schleswig-Holstein analysiert. Das untersuchte Material stammt von 1141 Jungbullen im Alter von 12 bis 15 Monaten. Der Untersuchungszeitraum erstreckte sich von 1975 bis 1984. Es ging 3604 Ejakulate in die Analyse ein. Die wesentlichsten Einfluβgröβen auf die Spermamerkmale waren Geburtssaison und Sprungsaison, Sprungabstand, Anzahl Sprünge je Tag, Libido und Deckvermögen. Aus dem Gesamtmaterial ergab sich eine enge Beziehung zwischen Libido und Deckvermögen (r_p=.87). Desweiteren konnten deutliche Beziehungen zwischen Dichte und pH-Wert, sowie Massenbewegung festgestellt werden (r_Di/pH= -.47; r_Di/MBW=.46). Darauf aufbauend errechnete sich eine ähnliche Beziehung zwischen pH-Wert und Massenbewegung (r_p=.42). Anhand der Halbgeschwisteranalyse wurden für die Spermamerkmale geringe (pH-Wert, h²=.065; Massenbewegung h²=.086) bis mittlere (Dichte, h²=.21; Volumen, h²=.13) Heritabilitäten geschätzt. Desweiteren ging aus den Ergebnissen hervor, daβ sich die Spermamerkmale Volumen und Massenbewegung seit dem Jahrgang 1980/81 und die Dichte seit dem Jahrgang 1975/76 verschlechtert haben. Nach Überprüfung der Umwelt- und der genetischen Einflüsse auf die Spermamerkmale konnte festgestellt werden, daβ die Verschlechterung der Spermamerkmale umweltbedingt war. Letztendlich ergab die Analyse, daβ Spermamerkmale, wie Volumen und Dichte, als rassenspezifisch anzusehen sind. Contents: Analysis of informations about the seminal quality of the Angler breed. The data were collected from 1141 young bulls in the age of 12–15 months at the A.I. station of Verband der Angler Rinderzüchter, Süderbrarup, Schleswig-Holstein (FRG). From 1975 to 1984 data of 3604 ejaculates were investigated. Significant factors influencing semen characters were 2^nd service at the same day, season of birth, season of service, libido and sexual behavior. There was narrow correlation between libido and sexual behavior (r_p=.87). As well there could be established a clear correlation between density and pH-value (r_p= -.47) and between density and motility (r_p=.46). Following heritabilities for semen characters were estimated: volume h²=.13, density h²=.21, pH h²=.065 and motility h²=.086). The results indicated, that the semen characters, volume and motility, have changed for the worse since the age-group 1980/81. The density already has changed for the worse since the age-group 1975/76. After checking the environmental influences and the genetic influences on semen characters, it could be established, that the worsening of the semen characters were caused by environmental influences. As well it could be recognized, that the semen characters, as volume and density, were considered as a peculiarity of a breed.     

Genetic parameters of the thick-to-thin albumen ratio and egg compositional traits in layer-type chickens

ABSTRACT

1. Generating a robust egg albumen is one of the major factors contributing to interior egg quality owing to its nutritive value and superior appearance. However, the genetic factors regulating the proportion of thick albumen are poorly understood.

2. In this study, 1330 eggs were collected from 450 Rhode Island White layers, aged 40 weeks, to measure egg compositional traits for three successive days. The restricted maximum likelihood method was applied to estimate genetic parameters for the thick-to-thin albumen ratio and other egg compositional traits. A univariate animal model was fitted to calculate heritability for each trait.

3. The heritabilities of egg weight, yolk weight, albumen height, Haugh units, percentages of yolk, thick albumen, thin albumen and the thick-to-thin albumen ratio were 0.32, 0.34, 0.28, 0.47, 0.61, 0.39, 0.31, and 0.45, respectively. The percentage of thick albumen was negatively correlated genetically with all traits, and percentage of thin albumen was negatively correlated genetically with all traits except for Haugh units. The thick-to-thin albumen ratio was positively correlated genetically with egg weight, albumen height and Haugh units, with correlations ranging from 0.21 to 0.54.

4. The results indicated that the percentage of thick albumen and the thick-to-thin albumen ratio were found to be moderately to highly heritable, and selection for the thick-to-thin albumen ratio could be conducive to the improvement of egg albumen quality.