The Experts below are selected from a list of 3360 Experts worldwide ranked by ideXlab platform
H. Atashi - One of the best experts on this subject based on the ideXlab platform.
-
association between age at first calving and Lactation performance Lactation Curve calving interval calf birth weight and dystocia in holstein dairy cows
PLOS ONE, 2021Co-Authors: H. Atashi, Anise Asaadi, Miel HostensAbstract:In the present study, records on 115,291 heifers distributed in 113 herds were used to investigate the association between age at the first calving (AFC) and Lactation performance, Lactation Curve, the length of the first calving interval (CI), calf birth weight (CBW), and the incidence of dystocia in Holstein heifers in Iran. Based on the AFC, the heifers were classified into eight classes: AFC of 541 to 690 d, 691 to 720 d, 721 to 750 d, 751 to 780 d, 781 to 810 d, 811 to 840 d, 841 to 900 d, and 901 to 1200 d (AFC1 to AFC8, respectively). Multiple regression mixed models were used to investigate the association between AFC and Lactation Curve parameters, partial and 305-d Lactation performance, 100- and 305-d SCS, and the length of the first calving (CI) interval. The mean (SD) and median AFC across all heifers was 760.2 (74.01) and 750 d, respectively. Of 115,291 heifers included, 28,192 and 7,602 heifers were, respectively, ≤ 720 and > 900 d when calving for the first time. More than 44% of the heifers were at 691 to 750 d (23 to 25 months) of age when calving for the first time. An increased AFC was associated with increased partial and 305-d Lactation performance, 100- and 305-d SCS, initial milk yield, milk production at the peak of Lactation, upward and downward slopes of the Lactation Curve. The 305-d fat percentage was associated with AFC; however, there was no association between AFC and 305-d protein percentage. An increased AFC was also associated with decreased milk production persistency, delayed peak time, longer CI, and higher calf birth weight. Compared to heifers calving for the first time between 691 to 780 d (23 to 26 months) of age, both increasing and decreasing AFC were associated with increased risk of dystocia. Controlling AFC is an important management factor in achieving a lower risk of dystocia, higher Lactation performance, lower SCS, and shorter length of the calving interval.
-
genome wide association for milk production and Lactation Curve parameters in holstein dairy cows
Journal of Animal Breeding and Genetics, 2020Co-Authors: H. Atashi, James L Ehrlich, Geert Opsomer, Mazdak Salavati, Jenne De Koster, M A Crowe, M HostensAbstract:The aim of this study was to identify genomic regions associated with 305-day milk yield and Lactation Curve parameters on primiparous (n = 9,910) and multiparous (n = 11,158) Holstein cows. The SNP solutions were estimated using a weighted single-step genomic BLUP approach and imputed high-density panel (777k) genotypes. The proportion of genetic variance explained by windows of 50 consecutive SNP (with an average of 165 Kb) was calculated, and regions that accounted for more than 0.50% of the variance were used to search for candidate genes. Estimated heritabilities were 0.37, 0.34, 0.17, 0.12, 0.30 and 0.19, respectively, for 305-day milk yield, peak yield, peak time, ramp, scale and decay for primiparous cows. Genetic correlations of 305-day milk yield with peak yield, peak time, ramp, scale and decay in primiparous cows were 0.99, 0.63, 0.20, 0.97 and -0.52, respectively. The results identified three windows on BTA14 associated with 305-day milk yield and the parameters of Lactation Curve in primi- and multiparous cows. Previously proposed candidate genes for milk yield supported by this work include GRINA, CYHR1, FOXH1, TONSL, PPP1R16A, ARHGAP39, MAF1, OPLAH and MROH1, whereas newly identified candidate genes are MIR2308, ZNF7, ZNF34, SLURP1, MAFA and KIFC2 (BTA14). The protein lipidation biological process term, which plays a key role in controlling protein localization and function, was identified as the most important term enriched by the identified genes.
-
association between gestation length and Lactation performance Lactation Curve calf birth weight and dystocia in holstein dairy cows in iran
Animal reproduction, 2019Co-Authors: H. Atashi, Anise AsaadiAbstract:In this study, 252,798 Lactations on 108,077 cows in 433 herds were used to determine the association between gestation length (GL) and Lactation performance, Lactation Curve, calf birth weight and dystocia in Holstein dairy cows in Iran. The GL averaged 278.1 ± 5.41 d, was categorized as short (SGL; at 1 SD below the population mean), average (AGL; the population mean ± 1 SD), or long (LGL; at least 1 SD above the population mean). Factors including parity, calf gender and calving season were associated with the GL. Primiparous cows with SGL had less Lactation performance than those with longer GL; however, there was no difference between those with AGL and LGL. Multiparous cows with longer GL always had more partial and 305-d Lactation performance. Primiparous cows with SGL produced less milk at the beginning of Lactation and at the peak than those with AGL or LGL; inverse trends were found for Lactation persistency, upward and downward slopes of the Lactation Curve. Within multiparous, a direct relationship was found between GL and the peak yield, where cows with longer GL always produced more milk at the peak. Multiparous cows with SGL produced less milk at the beginning of Lactation, reached their peaks later, had higher Lactation persistency and showed a lower upward slope of Lactation Curve than those with AGL or LGL. There was a direct relationship between GL and calf birth weight, where cows with longer GL had calves with more weight at the birth. Within primiparous, cows with SGL had the lowest and those with LGL had the highest rate of dystocia. However, multiparous cows with AGL had a lower rate of dystocia than those with SGL or LGL. Although there was a direct relationship between GL and Lactation performance, intermediate GL seems optimal when considering dystocia.
-
association of birth type and pregnancy type with Lactation performance and Lactation Curve in holstein dairy cows in iran
Iranian Journal of Applied Animal Science, 2018Co-Authors: H. Atashi, M. Dadpasand, Mohammad Javad Zamiri, Anise AsaadiAbstract:The association of birth type (single vs. double) and pregnancy type (single vs. double) with Lactation performance and Lactation Curve was investigated in Holstein cows in Iran. Data of 243298 Lactations on 138021 cows in 261 herds collected during January 2000 to December 2012 were used. The average twinning rate was 3.64% and ranged from 1.44% (primiparous) to 5.41% (multiparous). Factors associated with twining were calving season, calving year, herd, and parity. The rate of twinning increased from 2.49% in 2000 to 3.42% in 2012. The probability of twinning was higher in multiparous cows than that in primiparous [Odds ratio (OR) (95% confidence interval (CI))= 3.64 (3.44-3.84) for multiparous vs. primiparous cows]. The probability of twin pregnancy was higher in cows previously delivering twins than that in those delivering singles [OR (95% CI)= 3.17 (3.02-3.34) for cows delivering twins vs. cows delivering singles]. The Lactation Curve for cows delivering singles in previous gestation and pregnant with twins in subsequent gestation tended to be lower and flatter. The incidence of twin pregnancy was increased as the cow reached its peak yield earlier, and produced more milk at peak Lactation. Primiparous cows delivering singletons in their previous gestation and having twins in their subsequent gestation produced more 100-d, 200-d and 305-d milk than those pregnant with singletons. Multiparous cows that delivered singleton in previous gestation and were pregnant with twin in the subsequent gestation, produced more milk during the first 100-d and 200-d of Lactation than those pregnant with singles.
-
Estimation of Genetic Parameters for Lactation Curve Traits in Holstein Dairy Cows in Iran
Iranian Journal of Applied Animal Science, 2017Co-Authors: F. Saghanezhad, H. Atashi, M. Dadpasand, Mohammad Javad Zamiri, F. Shokri-sangariAbstract:The objectives were to estimate (co)variance components and genetic parameters for Lactation Curve traits in Holstein dairy cows in Iran. The used data were records on Holstein cows collected during January 2003 to December 2012 by the Animal Breeding Center of Iran (Karaj, Iran). In order to describe the Lactation Curve, an incomplete gamma function was fitted to 691200 test-day records on 96263 Lactations, 377696 test-day records on 52168 Lactations, and 182143 test-day records on 24951 Lactations for the first three parities, respectively. Lactation Curve traits that were analyzed included a scaling factor associated with initial yield, the inclining and declining slopes of the Curve, peak time, peak yield, 305-d milk yield and a Lactation persistency measure derived from the incomplete gamma function. The estimated heritability of Lactation Curve traits for the first, second and third Lactation ranged from 0.012 to 0.29, 0.017 to 0.15, and 0.02 to 0.13, respectively. Genetic correlations among Lactation Curve traits for the first, second and third Lactation ranged from -0.68 to 0.99, -0.84 to 0.98 and -0.90 to 0.94, respectively. The estimated repeatability of Lactation Curve traits ranged from 0.07 to 0.40. The moderate to large positive genetic correlations of 305-d milk yield with initial yield, peak yield and Lactation persistency suggest that one of these traits could be used as a selection criterion to improve all four traits. However, the peak yield and 305-d milk yield were more heritable than Lactation were persistency and initial yield.
M. Dadpasand - One of the best experts on this subject based on the ideXlab platform.
-
association of birth type and pregnancy type with Lactation performance and Lactation Curve in holstein dairy cows in iran
Iranian Journal of Applied Animal Science, 2018Co-Authors: H. Atashi, M. Dadpasand, Mohammad Javad Zamiri, Anise AsaadiAbstract:The association of birth type (single vs. double) and pregnancy type (single vs. double) with Lactation performance and Lactation Curve was investigated in Holstein cows in Iran. Data of 243298 Lactations on 138021 cows in 261 herds collected during January 2000 to December 2012 were used. The average twinning rate was 3.64% and ranged from 1.44% (primiparous) to 5.41% (multiparous). Factors associated with twining were calving season, calving year, herd, and parity. The rate of twinning increased from 2.49% in 2000 to 3.42% in 2012. The probability of twinning was higher in multiparous cows than that in primiparous [Odds ratio (OR) (95% confidence interval (CI))= 3.64 (3.44-3.84) for multiparous vs. primiparous cows]. The probability of twin pregnancy was higher in cows previously delivering twins than that in those delivering singles [OR (95% CI)= 3.17 (3.02-3.34) for cows delivering twins vs. cows delivering singles]. The Lactation Curve for cows delivering singles in previous gestation and pregnant with twins in subsequent gestation tended to be lower and flatter. The incidence of twin pregnancy was increased as the cow reached its peak yield earlier, and produced more milk at peak Lactation. Primiparous cows delivering singletons in their previous gestation and having twins in their subsequent gestation produced more 100-d, 200-d and 305-d milk than those pregnant with singletons. Multiparous cows that delivered singleton in previous gestation and were pregnant with twin in the subsequent gestation, produced more milk during the first 100-d and 200-d of Lactation than those pregnant with singles.
-
Estimation of Genetic Parameters for Lactation Curve Traits in Holstein Dairy Cows in Iran
Iranian Journal of Applied Animal Science, 2017Co-Authors: F. Saghanezhad, H. Atashi, M. Dadpasand, Mohammad Javad Zamiri, F. Shokri-sangariAbstract:The objectives were to estimate (co)variance components and genetic parameters for Lactation Curve traits in Holstein dairy cows in Iran. The used data were records on Holstein cows collected during January 2003 to December 2012 by the Animal Breeding Center of Iran (Karaj, Iran). In order to describe the Lactation Curve, an incomplete gamma function was fitted to 691200 test-day records on 96263 Lactations, 377696 test-day records on 52168 Lactations, and 182143 test-day records on 24951 Lactations for the first three parities, respectively. Lactation Curve traits that were analyzed included a scaling factor associated with initial yield, the inclining and declining slopes of the Curve, peak time, peak yield, 305-d milk yield and a Lactation persistency measure derived from the incomplete gamma function. The estimated heritability of Lactation Curve traits for the first, second and third Lactation ranged from 0.012 to 0.29, 0.017 to 0.15, and 0.02 to 0.13, respectively. Genetic correlations among Lactation Curve traits for the first, second and third Lactation ranged from -0.68 to 0.99, -0.84 to 0.98 and -0.90 to 0.94, respectively. The estimated repeatability of Lactation Curve traits ranged from 0.07 to 0.40. The moderate to large positive genetic correlations of 305-d milk yield with initial yield, peak yield and Lactation persistency suggest that one of these traits could be used as a selection criterion to improve all four traits. However, the peak yield and 305-d milk yield were more heritable than Lactation were persistency and initial yield.
-
association between dry period length and Lactation performance Lactation Curve calf birth weight and dystocia in holstein dairy cows in iran
Journal of Dairy Science, 2013Co-Authors: H. Atashi, Mohammad Javad Zamiri, M. DadpasandAbstract:Abstract In this study, 65,971 Lactations on 41,842 cows in 64 herds were used to determine the association between dry period length (DPL) and Lactation performance, Lactation Curve, calf birth weight, and the incidence of calving difficulty during the subsequent parity in Holstein dairy cows in Iran. The length of the dry period was classified into 7 categories: 0 to 35d, 36 to 50d, 51 to 60d, 61 to 70d, 71 to 85d, 86 to 110d, and 111 to 160d. Cows with the standard DPL (51 to 60d) produced more 305-d milk, fat, and protein over the next Lactation compared with those with shorter dry periods. Shorter dry periods (0 to 35d and 36 to 50d) were associated with lower initial milk yield, steeper inclining and declining slopes of the Lactation Curve, and higher milk persistency compared with dry period length of 51 to 60d. Peak Lactation was achieved later in cows with 0- to 35-d and 36- to 50-d dry period length than in those with dry period length of 51 to 60d. We also observed a relationship between DPL and calf birth weight: smaller calf birth weight was recorded with a dry period of 51 to 60d compared with longer dry periods. The incidence of calving difficulty did not differ in cows with 51- to 60-d dry period compared with cows with 0- to 35-d and 36- to 50-d dry periods. In conclusion, the results of this study did not support previous findings that suggested a shorter dry period could be beneficial to dairy production.
C.y. Lin - One of the best experts on this subject based on the ideXlab platform.
-
Genetic modification of the Lactation Curve by bending the eigenvectors of the additive genetic random regression coefficient matrix.
Journal of dairy science, 2007Co-Authors: K. Togashi, C.y. LinAbstract:The eigenvectors of the additive genetic random regression covariance (K) matrix contribute differentially to different parts of the Lactation Curve in response to genetic selection. It is, therefore, important to examine the genetic response patterns from the individual eigenvectors of the matrix K for the modification of the shape of the Lactation Curve. This study demonstrated a general methodology for imposing differential restrictions on different eigenvectors according to their effects on the shape of the Lactation Curve. A numerical example is given to illustrate the derivation and implementation of this procedure. Theoretically and experimentally, manipulating individual eigenvectors based on their individual effects on the shape of the Lactation Curve is more important than manipulating the joint effect of all the eigenvectors of K on the Lactation Curve. This described procedure provides a useful tool for simultaneous improvement of milk production and Lactation persistency by modifying the shape of the Lactation Curve.
-
modifying the Lactation Curve to improve Lactation milk and persistency
Journal of Dairy Science, 2003Co-Authors: K. Togashi, C.y. LinAbstract:Daily, stage and Lactation estimated breeding values (EBV) and the shape of the Lactation Curve for each cow are controlled by a unique set of random (genetic) regression coefficients under a test day model, thus providing a basis for genetic improvement of these characteristics. Three selection procedures were developed for simultaneous improvement of total Lactation milk and persistency: 1) index selection based on daily EBV, 2) index selection based on stage EBV, and 3) index selection based on random regression (RR) coefficients. A numerical example was given to demonstrate the computation of indexes based on stage EBV and based on RR coefficients. A conversion equation was derived to convert between genetic changes in EBV and RR coefficients. Index selection based on daily EBV would require the finding of 305 weighting factors for a Lactation period of 305 d, making it impractical to determine the weighting factors on a daily basis. Alternatively, a Lactation period was partitioned into a few stages to facilitate the construction of index selection based on stage EBV and index selection based on RR coefficients. These selection procedures make use of the annual genetic gains routinely computed in national genetic evaluations to restrict the genetic gains between different Lactation stages to achieve the desired Curve. When there is no prior knowledge of annual genetic gains, the proportional restriction of genetic gains between stages may be used. In summary, this study provides a simple means of modifying the Lactation Curve by manipulating genetic changes in different Lactation stages at a prespecified rate.
Nicolo Pietro Paolo Macciotta - One of the best experts on this subject based on the ideXlab platform.
-
genome wide association analysis in italian simmental cows for Lactation Curve traits using a low density 7k snp panel
Journal of Dairy Science, 2015Co-Authors: Nicolo Pietro Paolo Macciotta, Corrado Dimauro, D Vicario, Giustino Gaspa, Lorenzo Bomba, Massimo Cellesi, Paolo AjmonemarsanAbstract:High-throughput cow genotyping has opened new perspectives for genome-wide association studies (GWAS). Directly recorded phenotypes and several records per animal could be used. In this study, a GWAS on Lactation Curve traits of 337 Italian Simmental cows genotyped with the Illumina (San Diego, CA) low-density BeadChip (7K) was carried out. Scores of the first 2 principal components extracted from test-day records (7 for each Lactation) for milk yield, fat and protein percentages, and somatic cell score were used as phenotypes. The first component described the average level of the Lactation Curve, whereas the second summarized its shape. Data were analyzed with a mixed linear model that included fixed effects of herd, calving month, calving year, parity, SNP genotype, and random effects of animal and permanent environment. All statistically significant markers (Bonferroni corrected) were associated with the average level component (2 for milk yield, 9 for fat percentage, 6 for protein percentages, and 1 for somatic cell score). No markers were found to be associated with the Lactation Curve shape. Gene discovery was performed using windows of variable size, according to the linkage disequilibrium level of the specific genomic region. Several suggestive candidate genes were identified, some of which already reported to be associated with dairy traits, such as DGAT1. Others were involved in lipid metabolism, in protein synthesis, in the immune response, in cellular processes, and in early development. The large number of genes flagged in the present study suggests interesting perspectives for the use of low-density genotyped females for GWAS, also for novel phenotypes that are not currently considered as breeding goals.
-
characterization of the Lactation Curve in murciano granadina dairy goats
Small Ruminant Research, 2012Co-Authors: Juan Manuel Leon, Nicolo Pietro Paolo Macciotta, L T Gama, Carlos Barba, J V DelgadoAbstract:The Lactation Curve of Murciano-Granadina goats was studied by using records collected between 2004 and 2010 under its Official Dairy Recording program, which includes three milking control programs (Granada, Almeria and Cordoba). A total of 518,557 test-day records corresponding to 69,330 Lactations by 38,039 does in 130 herds were included in the analyses. Different mathematical models were fitted, and average Curves for region of production, parity, kidding season and type of kidding were estimated. A quadratic spline function gave the best fitting performance and provided a good description of the Murciano-Granadina Lactation Curve. All the factors studied affected both the scale of the Lactation Curve and its shape, with more distinct Curves in first Lactations, goats kidding in the summer and those producing singletons. When compared with later parities, first-parity does had a lower initial level of production, later and lower peak yield, and a smaller decline in milk production after the peak. Goats kidding in the Summer had a steep increase in milk yield up to the peak, which occurred earlier and with a higher yield than in other seasons, but seasonal effects differed slightly among regions. The Lactation Curve was flatter and with a later peak in goats producing single kids, and a steeper increase in yield up to the peak was observed as the number of kids increased.
-
detection of different shapes of Lactation Curve for milk yield in dairy cattle by empirical mathematical models
Journal of Dairy Science, 2005Co-Authors: Nicolo Pietro Paolo Macciotta, D Vicario, A CappioborlinoAbstract:Abstract The study of relationships between mathematical properties of functions used to model Lactation Curves is usually limited to the evaluation of the goodness of fit. Problems related to the existence of different Lactation Curve shapes are usually neglected or solved drastically by considering shapes markedly different from the standard as biologically atypical. A deeper investigation could yield useful indications for developing technical tools aimed at modifying the Lactation Curve in a desirable fashion. Relationships between mathematical properties and Lactation Curve shapes were analyzed by fitting several common functions (Wood incomplete gamma, Wilmink's exponential, Ali and Schaeffer's polynomial regression, and fifth-order Legendre polynomials) to 229,518 test-day records belonging to 27,837 Lactations of Italian Simmental cows. Among the best fits (adjusted r 2 higher than 0.75), the 3-parameter models (Wood and Wilmink) were able to detect 2 main groups of Curve shape: standard and atypical. Five-parameter models (Ali and Schaeffer function and the Legendre polynomials) were able to recognize a larger number of Curve shapes. The higher flexibility of 5-parameter models was accompanied by increased sensitivity to local random variation as evidenced by the bias in estimated test-day yields at the beginning and end of Lactation (border effect). Meaning of parameters, range of their values and of their (co) variances are clearly different among groups of Curves. Our results suggest that analysis based on comparisons between parameter values and (co)variances should be done carefully. Comparisons among parameter values and (co)variances could yield more robust, reliable, and easy to interpret results if performed within groups based on Curve shape.
-
the shape of sarda ewe Lactation Curve analysed by a compartimental model
Livestock Production Science, 1997Co-Authors: A Cappioborlino, Nicolo Pietro Paolo Macciotta, G PulinaAbstract:Abstract The Lactation Curve of the dairy Sarda sheep breed is characterised by a notable dimorphism. Empirical mathematical models used to represent the Lactation Curve of dairy cattle can describe the regular Curves but in the case of ‘irregular’ (or decayed) Curves, they give parameter estimates which are out of the range of significance. For this reason, a mechanistic mathematical model of the milk secretion process, based on a physiological theory of the mammary gland, was analysed. According to the different evolution of the processes of activation and inactivation of mammary secretory cells, the output of the model is a biexponential function or a monoexponential function. Lactations of sixty-four mature Sardinian ewes were analysed. The biexponential function fitted regular Lactation Curves ( R 2 = 0.87) and the monoexponential form fitted decayed Curves ( R 2 = 0.80). Parameter estimates were submitted to analysis of variance to estimate the influence of production level, type of lambing and udder health. The dimorphism of the Lactation Curve of the sheep does not seem to be affected by main environmental factors but a genetic influence could be hypothesised.
Anise Asaadi - One of the best experts on this subject based on the ideXlab platform.
-
association between age at first calving and Lactation performance Lactation Curve calving interval calf birth weight and dystocia in holstein dairy cows
PLOS ONE, 2021Co-Authors: H. Atashi, Anise Asaadi, Miel HostensAbstract:In the present study, records on 115,291 heifers distributed in 113 herds were used to investigate the association between age at the first calving (AFC) and Lactation performance, Lactation Curve, the length of the first calving interval (CI), calf birth weight (CBW), and the incidence of dystocia in Holstein heifers in Iran. Based on the AFC, the heifers were classified into eight classes: AFC of 541 to 690 d, 691 to 720 d, 721 to 750 d, 751 to 780 d, 781 to 810 d, 811 to 840 d, 841 to 900 d, and 901 to 1200 d (AFC1 to AFC8, respectively). Multiple regression mixed models were used to investigate the association between AFC and Lactation Curve parameters, partial and 305-d Lactation performance, 100- and 305-d SCS, and the length of the first calving (CI) interval. The mean (SD) and median AFC across all heifers was 760.2 (74.01) and 750 d, respectively. Of 115,291 heifers included, 28,192 and 7,602 heifers were, respectively, ≤ 720 and > 900 d when calving for the first time. More than 44% of the heifers were at 691 to 750 d (23 to 25 months) of age when calving for the first time. An increased AFC was associated with increased partial and 305-d Lactation performance, 100- and 305-d SCS, initial milk yield, milk production at the peak of Lactation, upward and downward slopes of the Lactation Curve. The 305-d fat percentage was associated with AFC; however, there was no association between AFC and 305-d protein percentage. An increased AFC was also associated with decreased milk production persistency, delayed peak time, longer CI, and higher calf birth weight. Compared to heifers calving for the first time between 691 to 780 d (23 to 26 months) of age, both increasing and decreasing AFC were associated with increased risk of dystocia. Controlling AFC is an important management factor in achieving a lower risk of dystocia, higher Lactation performance, lower SCS, and shorter length of the calving interval.
-
association between gestation length and Lactation performance Lactation Curve calf birth weight and dystocia in holstein dairy cows in iran
Animal reproduction, 2019Co-Authors: H. Atashi, Anise AsaadiAbstract:In this study, 252,798 Lactations on 108,077 cows in 433 herds were used to determine the association between gestation length (GL) and Lactation performance, Lactation Curve, calf birth weight and dystocia in Holstein dairy cows in Iran. The GL averaged 278.1 ± 5.41 d, was categorized as short (SGL; at 1 SD below the population mean), average (AGL; the population mean ± 1 SD), or long (LGL; at least 1 SD above the population mean). Factors including parity, calf gender and calving season were associated with the GL. Primiparous cows with SGL had less Lactation performance than those with longer GL; however, there was no difference between those with AGL and LGL. Multiparous cows with longer GL always had more partial and 305-d Lactation performance. Primiparous cows with SGL produced less milk at the beginning of Lactation and at the peak than those with AGL or LGL; inverse trends were found for Lactation persistency, upward and downward slopes of the Lactation Curve. Within multiparous, a direct relationship was found between GL and the peak yield, where cows with longer GL always produced more milk at the peak. Multiparous cows with SGL produced less milk at the beginning of Lactation, reached their peaks later, had higher Lactation persistency and showed a lower upward slope of Lactation Curve than those with AGL or LGL. There was a direct relationship between GL and calf birth weight, where cows with longer GL had calves with more weight at the birth. Within primiparous, cows with SGL had the lowest and those with LGL had the highest rate of dystocia. However, multiparous cows with AGL had a lower rate of dystocia than those with SGL or LGL. Although there was a direct relationship between GL and Lactation performance, intermediate GL seems optimal when considering dystocia.
-
association of birth type and pregnancy type with Lactation performance and Lactation Curve in holstein dairy cows in iran
Iranian Journal of Applied Animal Science, 2018Co-Authors: H. Atashi, M. Dadpasand, Mohammad Javad Zamiri, Anise AsaadiAbstract:The association of birth type (single vs. double) and pregnancy type (single vs. double) with Lactation performance and Lactation Curve was investigated in Holstein cows in Iran. Data of 243298 Lactations on 138021 cows in 261 herds collected during January 2000 to December 2012 were used. The average twinning rate was 3.64% and ranged from 1.44% (primiparous) to 5.41% (multiparous). Factors associated with twining were calving season, calving year, herd, and parity. The rate of twinning increased from 2.49% in 2000 to 3.42% in 2012. The probability of twinning was higher in multiparous cows than that in primiparous [Odds ratio (OR) (95% confidence interval (CI))= 3.64 (3.44-3.84) for multiparous vs. primiparous cows]. The probability of twin pregnancy was higher in cows previously delivering twins than that in those delivering singles [OR (95% CI)= 3.17 (3.02-3.34) for cows delivering twins vs. cows delivering singles]. The Lactation Curve for cows delivering singles in previous gestation and pregnant with twins in subsequent gestation tended to be lower and flatter. The incidence of twin pregnancy was increased as the cow reached its peak yield earlier, and produced more milk at peak Lactation. Primiparous cows delivering singletons in their previous gestation and having twins in their subsequent gestation produced more 100-d, 200-d and 305-d milk than those pregnant with singletons. Multiparous cows that delivered singleton in previous gestation and were pregnant with twin in the subsequent gestation, produced more milk during the first 100-d and 200-d of Lactation than those pregnant with singles.
