Traits In Parities Research Articles

Genetic parameters of production and reproduction traits of Egyptian buffaloes under subtropical conditions

This research was aimed to investigate the production and reproduction traits and their genetic parameters of Egyptian buffaloes under subtropical environment. Heritability, phenotypic, and genetic parameters were estimated for productive and reproduction traits of first parity This study revealed the averages TMY, 305-dMY, LL, BW, DP, SP, CI, and AFC were 2260, 2150 kg, 271 days, 38.63 kg, 210.50 days, 195.20 days, 586.86 days, and 36.61 months, respectively. The heritability estimates for productive traits of the first lactation were 0.61, 0.52, 0.47, 0.20, and 0.23 for TMY, 305-dMY, LL, DP, and BW, respectively. Heritability estimates for reproductive traits SP, CI, and AFC were 0.07, 0.09, and 0.35, respectively. Genetic correlations of most of the investigated first parity traits were positive, with an exception of DP. The genetic correlation was negative between SP and BW, and between AFC and LL. Phenotypic correlations of the first parity among all investigated traits were positive except between DP and TMY, 305-dMY, LL, BW, and AFC. High and moderate heritability estimates indicated that the opportunity of genetic upgrading of these parameters could be achieved owing to sire selection. Selection for high milk yield will be associated with genetic improvement in lactation period and birth weight.

Estimation of genetic parameters for traits associated with reproduction, lactation, and efficiency in sows.

Increased milk production due to high litter size, coupled with low feed intake, results in excessive mobilization of sow body reserves during lactation, which can have detrimental effects on future reproductive performance. A possibility to prevent this is to improve sow lactation performance genetically, along with other traits of interest. The aim of this study was to estimate breed-specific genetic parameters (by parity, between parities, and across parities) for traits associated with lactation and reproduction in Yorkshire and Landrace sows. Performance data were available for 2,107 sows with 1 to 3 parities (3,424 farrowings total). Sow back fat, loin depth and BW at farrowing, sow feed intake (SFI), and body weight loss (BWL) during lactation showed moderate heritabilities (0.21 to 0.37) in both breeds, whereas back fat loss (BFL), loin depth loss (LDL), and litter weight gain (LWG) showed low heritabilities (0.12 to 0.18). Among the efficiency traits, sow lactation efficiency showed extremely low heritability (near zero) in Yorkshire sows but a slightly higher (0.05) estimate in Landrace sows, whereas sow residual feed intake (SRFI) and energy balance traits showed moderate heritabilities in both breeds. Genetic correlations indicated that SFI during lactation had strong negative genetic correlations with body resource mobilization traits (BWL, BFL, and LDL; -0.35 to -0.70), and tissue mobilization traits in turn had strong positive genetic correlations with LWG (+0.24 to +0.54; < 0.05). However, SFI did not have a significant genetic correlation with LWG. These genetic correlations suggest that SFI during lactation is predominantly used for reducing sow body tissue losses, rather than for milk production. Estimates of genetic correlations for the same trait measured in parities 1 and 2 ranged from 0.64 to 0.98, which suggests that first and later parities should be treated as genetically different for some traits. Genetic correlations estimated between traits in parities 1 and 2 indicated that BWF and BWL measured in parity 1 can be used as indicator traits for SFI and SRFI measured in parities 1 and 2. In conclusion, traits associated with lactation in sows have a sizable genetic component and show potential for genetic improvement.

Genetic analysis of calving traits by the multi-trait individual animal model

Five alternative models were applied for analysis of dystocia and stillbirth in first and second parities. Models 1 and 2 were included only to estimate the parameters required for model 4, and models 3 and 5 are included only as comparisons to the model 4 estimates. Variance components were estimated by multi-trait REML, including cows with valid calving records for both parities. For the effects of sire of calf on first and second parities, variance components were estimated including only calvings with the same sire of calf for both parities. All heritabilities for the cow effect were quite low, but higher for dystocia than for stillbirth and higher in first parity. The sire-of-calf heritabilities were higher than the cow effect heritabilities, except for stillbirth in parity 2. Unlike the effect of cow correlations, all sire of calf correlations were >0.6, and the correlations for the same trait in parities 1 and 2 were >0.9. Thus, a multi-trait analysis should yield a significant gain in accuracy with respect to the sire of calf effects for bulls not mated to virgin heifers. A multi-trait individual animal model algorithm was developed for joint analysis of dystocia and stillbirth in first and second parities. Relationships matrices were included both for the effects of cow and sire of calf. In addition, random herd-year-season and fixed sex of calf effects were included in the model. Records were preadjusted for calving month and age. A total of 899,223 Israeli Holstein cows with first calvings since 1985 were included in the complete analysis. Approximate reliabilities were computed for both sire of cow and sire of calf effects. Correlations between these reliabilities and reliabilities obtained by direct inversion of the coefficient matrix for a sire of cow-sire of calf model were all close to 0.99. Phenotypic trends for cows born from 1983 through 2007 were economically unfavorable for dystocia and favorable for stillbirth in both parities. Genetic trends were economically unfavorable for both dystocia and stillbirth in first parity. First-parity sire of calf trends were unfavorable for dystocia, but favorable for stillbirth. All environmental trends were nearly zero. Regressions of evaluations of the complete analysis on a model including only calvings before 2011 were all >0.8. All evaluations met the Interbull Method 3 criterion for unbiasedness. Model 4, which computed genetic evaluations for all animals for all 4 traits accounting for all known relationships and correlations among the traits, is recommended for routine genetic evaluation of calving traits.

The fat cover in gilts in relation to body condition and reproduction

A study was conducted in a set of hybrid gilts of F1 generation of Czech Large White x Czech Landrace breeds coming from a multiplication herd. The objective of the study was to test a possibility of using the measured traits, i.e. backfat thickness (BT) and lean meat content (LM), for objective determination of changes in the body condition score of gilts during rearing and in relation to their subsequent fertility in parities 1. At the ultrasonic measurement in the multiplication herd the purchased gilts showed the average daily gain (ADG) from birth 612.5 g, average backfat thickness (ABT) 8.34 mm, loin muscle depth (LMD) 48.83 mm and LM 62.26%. At the first determination of own performance traits in a production herd the values of ABT, LMD and LM were 13.26 mm, D 59.29 mm and 58.83%, respectively. In a subsequent measurement (at the onset of standing heat) the respective values of ABT, LMD and LM were 15.15 mm, 62.31 mm and 57.42%. Correlation coefficients for the measured traits of own performance in relation to reproductive traits in parities 1 were mostly low, statistically insignificant.

Response to intensity of reproduction in mouse lines resistant or susceptible to fescue toxicosis

Our objective was to examine whether mouse lines divergently selected for response to fescue toxicosis differed in the impact of increasing reproductive intensity on growth, final weight or first and second parity reproduction. Resistant (R) and susceptible (S) females were never mated (NR), mated only once (low reproduction, LR), mated after their first litter was weaned (moderate reproduction, MR) or paired continuously with a male (high reproduction, HR), allowing concurrent pregnancy and lactation. Final weight was significantly higher in mated than in not mated females (31.6 +/- 0.6, 35.9 +/- 0.6, 36.8 +/- 0.6 and 37.2 +/- 0.5 g for NR, LR, MR and HR females respectively), but the effect of increasing reproductive intensity was similar in both lines. Neither genetic line, reproductive treatment (LR and MR versus HR) nor their interaction affected first parity traits of dams or pups. In second parity, S dams produced larger litters at birth and weaning and heavier litters at birth than R dams, and MR dams produced more pups and heavier litters than HR dams. As with first litters, however, line by reproductive treatment interactions were not significant or important. Concurrent pregnancy and lactation (the HR treatment) had a similar dampening impact on the expected increase in litter size between first and second parity of both lines. Thus, lines divergently selected for toxicosis response did not differ significantly in the impact of increasing reproductive intensity on dam or pup growth, reproductive output through two parities or mature size. This conclusion should not be generalized. Selection responses in livestock should be monitored to ensure that improvement in one trait does not lead to deterioration in others.

Heritability for reproduction traits in Polish and Norwegian populations of dairy goat

Estimation and verification of the variance components of the reproduction traits in dairy goats was the purpose of the investigation. The study included Polish and Norwegian populations. Since the numbers of goats were generally lower and the pedigree information poorer, in the Polish population, the results obtained for the Norwegian one were treated as the reference. The Polish data included records on 9283 goats maintained in herds from 1983 till 2001. The information on the first parity litter size (LS1), number of kids born alive (NBA1), and total losses (TL1) regarded 8479 does while the data on the second parity traits (LS2, NBA2, TL2) included 5729 does. Age at first kidding (AK1) was known for 7370 does and age at second kidding (AK2) and kidding interval (KI)—for 4545 does. The pedigree included 13 618 animals with the eldest born in 1977. The Norwegian data set covered 68 240 does with 64 903 having recorded LS1 and K1, 51 266—LS2 and AK2, and 45 704—KI. The goats were maintained from 1991 till 2002. The pedigree data covered 150 677 animals with the eldest born in 1966. The variance components were estimated with the REML method using animal model. The heritability estimates of LS1, NBA1, TL1, and AK1 were 0.14, 0.11, 0.04, 0.13; of LS2, NBA2, TL2, and AK2—0.11, 0.09, 0.04, and 0.13, in the Polish population. The heritability of KI reached only 0.015. In the Norwegian population the heritabilities of LS1, LS2, and KI were 0.18, 0.13, and 0.03, respectively. The estimates of heritabilities in the second parity were lower or at most equal to those in the first one. The magnitude of the heritability estimates for LS1, LS2, NBA1, and NBA2 indicate possibility of an effective selection for those traits.