Genetic parameters for milk,growth, and reproductive traits in Guzerá cattle under tropical conditions

Tropical Animal Health and Production - This study aimed to estimate the genetic parameters of milk (305-day milk yield (MY305)), growth (weaning weight (WW), yearling weight (YW), and weight at...     

Genetic parameters for energy balance, fat /protein ratio, body condition score and disease traits in German Holstein cows

Various health problems in dairy cows have been related to the magnitude and duration of the energy deficit post partum. Energy balance indicator traits like fat/protein ratio in milk and body condition score could be used in selection programmes to help predicting breeding values for health traits, but currently there is a lack of appropriate genetic parameters. Therefore, genetic correlations among energy balance, fat/protein ratio, and body condition score, and mastitis, claw and leg diseases, and metabolic disorders were estimated using linear and threshold models on data from 1693 primiparous cows recorded within the first 180 days in milk. Average daily energy balance, milk fat/protein ratio and body condition score were 8 MJ NEL, 1.13 and 2.94, respectively. Disease frequencies (% cows with at least one case) were 24.6% for mastitis, 9.7% for metabolic disorders and 28.2% for claw and leg diseases. Heritability estimates were 0.06, 0.30 and 0.34 for energy balance, fat/protein ratio and body condition score, respectively. For the disease traits, heritabilities ranged between 0.04 and 0.15. The genetic correlations were, in general, associated with large standard errors, but, although not significant, the results suggest that an improvement of overall health can be expected if energy balance traits are included into future breeding programmes. A low fat/protein ratio might serve as an indicator for metabolic stability and health of claw and legs. Between body condition and mastitis, a significant negative correlation of -0.40 was estimated. The study provides a new insight into the role energy balance traits can play as auxiliary traits for robustness of dairy cows. It was concluded that both, fat/protein ratio and body condition score, are potential variables to describe how well cows can adapt to the challenge of early lactation. However, the genetic parameters should be re-estimated on a more comprehensive data set.     

Genetic analysis for growth traits of prolific Garole × Malpura (GM) sheep

The FecB gene of Garole sheep was introgressed into non-prolific Malpura sheep to evolve a new prolific sheep strain Garole × Malpura (GM), suitable for semi-arid conditions. The present study was conducted to evaluate the impact of breeding program on production profile of GM sheep and to estimate the genetic parameters for growth traits of GM sheep. Overall prolificacy increased significantly in the new strain as compared to the native Malpura sheep. In the GM flock of F2 and F2 onwards generation 35.31% single, 55.83% twins, 8.16% triplet and 0.70% quadruplets were obtained during lambing. Over the years, prolificacy in the flock has increased significantly. Over all least squares means for birth weight, 3, 6, 9, 12 month weight, pre-weaning gain (ADG1) and post-weaning gain (ADG2) were 1.82 ± 0.03, 9.44 ± 0.18, 14.00 ± 0.24, 16.56 ± 0.33, and 19.32 ± 0.35 kg, and 84.08 ± 1.84 and 35.19 ± 0.99 g, respectively. Majority of the fixed effects had significant influence on the performance traits. The heritability estimates for birth, 3, 6, 9, 12 month weight, ADG1 and ADG2 were 0.30 ± 0.11, 0.22 ± 0.09, 0.23 ± 0.10, 0.27 ± 0.10, 0.30 ± 0.11, 0.17 ± 0.08, and 0.17 ± 0.10, respectively. Modest rate of genetic progress seems possible for these traits under selection. The genetic and phenotypic correlations among different body weights were moderate to high and positive. The genetic correlation of pre and post-weaning daily gains with body weight traits were also high and positive.     

Effect of different roughages sources on performance,milk composition,fatty acid profile,and milk cholesterol content of feedlot feed crossbred cows (Holstein × Zebu)

Tropical Animal Health and Production - The aim of the study was to evaluate the effect of different forage sources in diets for feedlot dairy cows and their implications on production,...     

Is there a special mechanism behind the changes in somatic cell and polymorphonuclear leukocyte counts,and composition of milk after a single prolonged milking interval in cows?

Background

A single prolonged milking interval (PMI) e.g. after a technical stop in an automated milking system is of concern for the producer since it is associated with a short-lasting increase in milk somatic cell count (SCC), which is a major quality criterion used at the dairy plants. The content of polymorphonuclear leukocytes (PMN) and how the milk quality is influenced has not been much investigated. The SCC peak occurs without any obvious antigen challenge, possibly indicating a different leukocyte attraction mechanism after a PMI than we see during mastitis.

Methods

Composite cow milk samples were taken at the milkings twice daily during 7 days before and 5 days after a PMI of 24 h. Milk was analyzed for SCC, PMN, fat, protein and lactose, and at some occasions also casein and free fatty acids (FFA).

Results

During the PMI the proportion of milk PMN increased sharply in spite of marginally increased SCC. The peak SCC was not observed until the second milking after the PMI, in the afternoon day 1. However, the peak SCC value in morning milk did not occur until one day later, concomitantly with a decrease in the proportion of PMN. After declining, SCC still remained elevated while PMN proportion was decreased throughout the study as was also the milk yield, after the first accumulation of milk during the PMI. Milk composition was changed the day after the PMI, (increased fat and protein content; decreased lactose, whey protein and FFA content) but the changes in the following days were not consistent except for lactose that remained decreased the rest of the study.

Conclusion

The PMI resulted in increased SCC and proportion of PMN. Additionally, it gave rise to minor alterations in the milk composition in the following milkings but no adverse effect on milk quality was observed. The recruitment of PMN, which was further enhanced the first day after the PMI, appeared to be independent of milk volume or accumulation of milk per se. Hence, we suggest that there is a special immunophysiological/chemoattractant background to the increased migration of leukocytes into the milk compartment observed during and after the PMI.     

Evaluation of agronomic traits and nutrient absorption of an F4 recombinant inbred line of Chinese milk vetch (Astragalus sinicus)北大核心CSCD

In this research an F4 inbred line of Chinese milk vetch was constructed using Minzi No.7 milk vetch (Astragalus sinicus) as the female parent and the variety Xinyang as the male parent. For 18 strains in this population, the agronomic traits and nutrient absorption status were evaluated in a pot experiment at the full flowering stage, in order to use the results as a reference for screening superior milk vetch strains. Differences between plant strains were found. Correlation analysis showed that fresh weight, dry weight and accumulation of nitrogen, phosphorus and kalium were highly correlated, and were drivers of plant nutrient absorption, while plant height, branch number and leaf number were important factors affecting the fresh weight and dry weight of the plant. Principal component analysis showed that the main indexes such as shoot fresh and dry weights, and accumulation of nitrogen, phosphorus and kalium in the shoots could be used as indexes of Chinese milk vetch performance. In cluster analysis with the distance coefficient d=25, the 18 tested strains could be classified into three groups, of which Group Ⅰ had 4 strains (m83xzh-1-4-4, m83xzh-1-4-6, m83xzh-1-4-8, and m83xzh-1-4-13) with excellent multivariate trait scores. The best performing Chinese milk vetch strain in this evaluation was m83xzh-1-4-4. For this strain, the total plant nitrogen, phosphorus and kalium nutrient accumulation, accumulation of phosphorus and kalium in the shoots and accumulation of nitrogen and kalium in the roots were highest among the18 strains tested and were 11.00 mg·pot-1, 145.18 mg·pot-1, 22.15 mg·pot-1 and 15.27 mg·pot-1, respectively. The herbage fresh yield of m83xzh-1-4-4 was 44.63 g·pot-1 and ranked second among the 18 strains tested. This study provides technical data which may be useful in future breeding work to develop new milk vetch varieties. © 2022, Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

The effect of different dietary levels of sodium and chloride on performance and blood parameters in goslings (1–28 days of age)

A total of 702 1-day-old male Jiangnan White goslings were used to study the effects of varying levels of Na⁺ and Cl⁻ on their growth performance and blood parameters. In this experiment, goslings were randomly allotted to nine treatments, with six pens per treatment in a 3 × 3 factorial arrangement, and fed diets with three concentrations of added Na⁺ (0.10%, 0.15% and 0.20%) and three concentrations of added Cl⁻ (0.15%, 0.20% and 0.25%). The purpose of this experiment was to investigate the sensitivity of goslings to Na⁺ and Cl⁻ during brooding to determine the appropriate levels of Na⁺ and Cl⁻ in their feed. The results are as follows: (a) Different levels of Na⁺ and Cl⁻ in the diet, especially low Na⁺ and Cl⁻, significantly affected the body weight (BW), average daily gain (ADG) and feed/gain ratio (F/G) of the 28-day-old goslings (p < .05). But Na⁺ × Cl⁻ has no significant effect on water consumption (p > .05). (b) Serum concentrations of urea increased linearly with Na⁺ content (p < .05). Serum concentrations of creatinine (CR) and uric acid (UA) increased linearly with Cl⁻ content (p < .05). (c) Na⁺ × Cl⁻ has a significant impact on the serum sodium (Na) and chlorine (Cl; p < .05). The content of serum Na and Cl increased linearly with increasing levels of Na⁺ and Cl⁻. These results show that low levels of Na⁺ and Cl⁻ had significant adverse effects on the growth of 1- to 28-day-old goslings. The results of the experiment support a recommendation to supplement the diet of goslings with 0.20% Cl⁻ and not <0.15% Na⁺.     

Evaluation of candidate genotype of leptin gene associated with fertility and production traits in Hardhenu (Bos taurus × Bos indicus) cattle

The present study was conducted on Hardhenu cattle to screen genomic region of leptin gene with an objective to find the association of genotypes with fertility and production traits. The association analysis with traits under study was analysed by least squares analysis of variance by taking SNPs genotype as fixed effects in the statistical model. The genotypic frequencies with respect to targeted loci g.92450765 G > A indicated that AG (0.54) genotype was highest in Hardhenu cattle. Chi-squared tests showed that g.92450765G > A SNP meet with the Hardy–Weinberg equilibrium (p > .05).The association analysis revealed significant association of genotypes with total milk yield (TMY) and 305 days milk yield (MY) (p < .05). Service period (SP) and calving interval (CI) were also found significantly associated with genotypes (p < .05). Whereas, lactation length (LL), dry days (DD) and age at first calving (AFC) did not divulge any significant association with genotype. The AG and GG genotypes were associated with higher milk yields as compared to AA genotype, indicating that allele G was associated with superior milk performance. However, AA genotyped cattle found to be favourable with SP, CI and artificial insemination (AI) per conception compared to AG and GG genotyped cows. Chi-square analysis revealed that genetic variants of g.92450765 G > A SNP of leptin gene differ significantly with regard to reproductive disorders incidence (p < .05). The frequency of GG genotype (88.89%) in the affected animal group was very high followed by AG. The animals with GG genotype were found to be more susceptible to reproductive disorders as suggested by the higher odd ratio value (16.00) in logistic model. These observations and their differential association with the fertility and production traits can be utilized as an aid to selection for genetic improvement of antagonistic traits in dairy cows.     

Technical note: A novel method for routine genotyping of the G allele of β-casein (CSN2) and T allele of κ-casein (CSN3) in a sheep population using LightCycler

The goal of this work was to develop a protocol for rapid genotyping of A and G variants at the CSN2 locus and genotyping of T and C variants at the CSN3 locus in sheep breeds (Sumava and Valachian) by means of PCR and LightCycler analysis. The LightCycler technique combines rapid and efficient in vitro amplification of DNA in glass capillaries with melting curve analysis based on fluorescence resonance energy transfer for the sensitive detection of point mutation. The A variant had a greater frequency (Sumava, 0.778; Valachian, 0.835) than did variant G (Sumava, 0.222; Valachian, 0.165) in both sheep breeds. The CSN3 locus was found to be monomorphic, with no polymorphism identified in either population.     

Heritabilities and genetic trends for elbow score as recorded by the New Zealand Veterinary Association Elbow Dysplasia Scheme (1992–2013) in four breeds of dog

AIM: To estimate the heritability of the New Zealand Veterinary Association (NZVA) elbow phenotype, obtain estimated breeding values (EBV) for the worst-elbow score and estimate the genetic trends for this trait in four populous breeds of dogs, using the records from the NZVA Canine Elbow Dysplasia Scheme database (1992–2013).

METHODS: Overall, 4,070 elbow records from a pedigree of 11,311 dogs were available for animals scored between 1992 and 2013. The worst elbow score between the left and right elbows was identified for each dog and used for EBV analysis. Estimates of heritability and EBV for the elbow score of dogs from German Shepherd dog, Labrador Retriever, Golden Retriever and Rottweiler breeds were obtained using restricted maximum likelihood procedures with a within-breed linear animal model. The model included the fixed effects of sex and birth year, with age at scoring as a covariable, and the random effect of animal. Genetic trends for the worst-elbow score were calculated as the regression coefficient of the EBV, weighted by reliabilities, on year of birth.

RESULTS: The estimates of heritability for worst-elbow score were 0.25 (SE 0.06) in German Shepherd dogs, 0.46 (SE 0.06) in Labrador Retrievers, 0.18 (SE 0.07) in Golden Retrievers and 0.29 (SE 0.11) in Rottweilers. The genetic trend for German Shepherd dogs was ?0.0082 (SE 0.0015), for Labrador Retrievers was ?0.0016 (SE 0.0016), for Golden Retrievers was ?0.0033 (SE 0.0010) and for Rottweilers was ?0.0070 (SE 0.0023) units per annum, which were different from zero (p<0.01) in all breeds except Labrador Retrievers.

CONCLUSIONS AND CLINICAL RELEVANCE: A small but favourable response to selection was achieved by three of the four breeds in the study period; during which selection for elbow traits has been largely voluntary. While the magnitude of genetic change in terms of elbow units per annum may appear small, it must be remembered that elbow scoring grades only range from 0–3. Greater improvement may be possible if compulsory screening was a requirement for pedigree breeding stock, and if greater selection pressure were applied on the basis on an individual’s EBV, rather than the worst-elbow score alone. The maintenance of an open registry, with transparency of EBV information made available to all breeders, may enhance selection intensity opportunities and potentially assist with the process and progress of breeding selection.     

Evaluation of three tidal volumes (10, 12 and 15 mL kg−1) in dogs for controlled mechanical ventilation assessed by volumetric capnography: a randomized clinical trial

Objective

To evaluate three routinely used tidal volumes (V_T; 10, 12 and 15 mL kg^?1) for controlled mechanical ventilation (CMV) in lung-healthy anaesthetized dogs by assessing alveolar ventilation (VT_alv) and dead space (DS).