Study of genetic and environment trends for milk fat yield trait in an Iranian dairy herd

2007 ◽  
Vol 2007 ◽  
pp. 158-158
Author(s):  
Mohammad Hassan Jahandar ◽  
Mohhamad Moradi Shahre Babak ◽  
Mahdi Elahi Torshizi
Keyword(s):  
Milk Fat ◽  
Genetic Improvement ◽  
Selection Index ◽  
Dairy Herd ◽  
Population Variation ◽  
Fat Percentage ◽  
Foreign Countries ◽  
Yield Trait ◽  
Fat Yield ◽  
Genetic Trends

In order to evaluate genetic improvement in a selected population, variation resulted from environment and genetics should be dissociated. Because of the positive genetic correlation between milk fat yield and milk and protein yield, selection for milk production has often resulted in an increase in fat and protein yields however response for fat percentage is negative. However positive genetic trends between 0.73 to 0.95 kg per annum for milk fat yield in Holstein cattle have been reported in some studies that milk fat yield had less importance in selection index, also negative values are reported. Based on previous research, genetic improvement of milk fat yield up to 1 percent due to selection is possible and from a theoretical view, an improvement of about 2 percent is reported. With attention to selection in the herd and using progeny tested semen from foreign countries that have suitable genetic potential, this study was accomplished in order to estimate genetic parameters for milk fat and investigate genetic and environmental trends during 1990 to 2001.

The effect of udder infections on the lactation yield of milk and milk solids

1960 ◽  
Vol 27 (1) ◽  
pp. 115-120 ◽  
Author(s):  
J. O'Donovan ◽  
F. H. Dodd ◽  
F. K. Neave
Keyword(s):  
Antibiotic Therapy ◽  
Milk Fat ◽  
Milk Composition ◽  
Fat Percentage ◽  
The Mean ◽  
Fat Yield ◽  
Milk Solids

SummaryData available for fifty cows mainly infected with Staphylococcus pyogenes have been analysed to determine the effects of udder infections and mastitis on milk, fat and solids-not-fat yield and on fat and solids-not-fat percentages over full lactations.It was found that lactation yields of milk, solids-not-fat and fat were depressed by 10, 11 and 12% respectively in the presence of infection. These depressions were significant (P < 0·05). The composition of the milk averaged over whole lactations was not significantly affected (P > 0·05), although the mean solids-not-fat percentage of the milk was significantly depressed by 0·196±0·092 during the period of infection.It is suggested that the depressions in lactation yield and changes in milk composition would have been greater in the absence of antibiotic therapy for mastitis.

A practical future-scenarios selection tool to breed for heat tolerance in Australian dairy cattle

2017 ◽  
Vol 57 (7) ◽  
pp. 1488 ◽  
Author(s):  
Thuy T. T. Nguyen ◽  
Ben J. Hayes ◽  
Jennie E. Pryce
Keyword(s):  
Heat Tolerance ◽  
Milk Fat ◽  
Heat Load ◽  
Selection Index ◽  
Dairy Herd ◽  
Breeding Value ◽  
Future Scenarios ◽  
Selection Tool ◽  
Temperature Humidity Index ◽  
Humidity Index

Climate change will have an impact on dairy cow performance. When heat stressed, animals consume less feed, followed by a decline in milk yield. Previously, we have found that there is genetic variation in this decline. Selection for increased milk production, a major breeding objective, is expected to reduce heat tolerance (HT), as these traits are genetically unfavourably correlated. We aimed to develop a future-scenarios selection tool to assist farmers in making selection decisions, that combines the current national dairy selection index, known as the balanced performance index (BPI), with a proposed HT genomic estimated breeding value (GEBV). Heat-tolerance GEBV was estimated for 12 062 genotyped cows and 10 981 bulls, using an established genomic-prediction equation. Publicly available future daily average temperature and humidity data were used to estimate mean daily temperature–humidity index for each dairy herd. An economic estimate of an individual cow’s heat-tolerance breeding value (BV_HT) was calculated by multiplying head-tolerance GEBVs for milk, fat and protein by their respective economic values that are already used in the BPI. This was scaled for each region by multiplying BV_HT by the heat load, which is the temperature–humidity index units exceeding the threshold per year at a particular location. BV_HT were incorporated into the BPI as: BPI_HT = BPI + BV_HT; where BPI_HT is the ‘augmented BPI’ breeding value including HT. A web-based application was developed enabling farmers to predict the future heat load of a herd and take steps to aim at genetic improvement in future generations by selecting bulls and cows that rank high for the ‘augmented BPI’.

PRODUCTION TRAITS OF RED AND WHITE RELATIVE TO BLACK AND WHITE HOLSTEINS

1988 ◽  
Vol 68 (1) ◽  
pp. 299-303
Author(s):  
P. G. SULLIVAN ◽  
J. W. WILTON ◽  
B. J. VAN DOORMAAL
Keyword(s):  
Milk Fat ◽  
Milk Protein ◽  
Dairy Production ◽  
Production Traits ◽  
Black And White ◽  
Genetic Overlap ◽  
Fat Yield ◽  
And Performance ◽  
Genetic Evaluations ◽  
Genetic Trends

Canadian red and white (RW) and black and white (BW) Holsteins were compared for several production traits based on genetic evaluations of 32 RW and 883 BW bulls, and performance data of 4161 RW and 8691 BW cows. Differences (P < 0.05), favoring BW, were observed for milk and milk fat yield of cows, and for milk fat and milk protein yield evaluations of bulls. There was, however, a large genetic overlap between the populations for all traits studied. Pleiotropic effects associated with the color gene were not detected as being important. Phenotypic trends for milk yield, milk fat yield, and milk fat percent were significantly greater for BW than RW cows (P < 0.01). Genetic trends were greater for RW cows, though not significantly (P > 0.05). Key words: Dairy production, genetic trends, Holstein (red and white), Holstein (black and white)

Assessment of the Canadian model predicting daily milk yield and milk fat percentage using single-milking dairy herd improvement samples

2019 ◽  
Vol 99 (3) ◽  
pp. 521-531
Author(s):  
M. Duplessis ◽  
R. Lacroix ◽  
L. Fadul-Pacheco ◽  
D.M. Lefebvre ◽  
D. Pellerin
Keyword(s):  
Milk Yield ◽  
Milk Fat ◽  
Dairy Herd ◽  
Fat Percentage ◽  
Daily Milk Yield ◽  
Daily Milk

scholarly journals SIRE-SON CORRELATIONS OF GENETIC EVALUATIONS FOR FAT PERCENTAGE IN HOLSTEIN-FRIESIANS

1987 ◽  
Vol 67 (3) ◽  
pp. 631-635 ◽  
Author(s):  
T. E. ALI ◽  
L. R. SCHAEFFER
Keyword(s):  
Key Words ◽  
Artificial Insemination ◽  
Milk Fat ◽  
Genetic Parameters ◽  
Direct Calculation ◽  
Fat Percentage ◽  
Low Correlation ◽  
Fat Yield ◽  
Genetic Evaluations ◽  
Selection Of

The correlation between sire and son genetic evaluations for fat percentage has been shown to be lower than corresponding correlations for milk or fat yield for the population of bulls in artificial insemination. The purpose of this study was to determine the cause of this low correlation. Based on 302 935 first-lactation daughters of 11 396 sires, the heritabilities of milk, fat and fat percentage were 0.28, 0.27 and 0.52, respectively. Indirect versus direct calculation of sire evluations for fat percentage were correlated at 0.997, and resulting sire-son correlations were 0.45 for directly calculated proofs and 0.43 for indirectly calculated proofs. The low sire-son correlations were due to the intense selection of sires of sons, especially for fat percentage, which resulted in a change in genetic parameters among the bulls used as sires of sons compared to the parameters in the overall population. Key words: Fat percentage, pedigree indexing, dairy sires

scholarly journals Genetic and phenotypic trends for age at first calving and milk yield and compositions in Holstein dairy cows

2011 ◽  
Vol 54 (4) ◽  
pp. 338-347
Author(s):  
N. G. Hossein-Zadeh
Keyword(s):  
Milk Yield ◽  
The Other ◽  
Protein Yield ◽  
Fat Percentage ◽  
Milk Traits ◽  
Age At First Calving ◽  
Other Hand ◽  
Fat Yield ◽  
Over Time ◽  
Genetic Trends

Abstract. Calving records from the Animal Breeding Center of Iran collected from January 1990 to December 2007 and comprising 207 106 first calving events of Holsteins from 2 506 herds were analysed using linear sire models to estimate genetic trends for age at first calving (AFC) and milk traits. Genetic trends were obtained by regressing yearly mean estimates of breeding values on year of birth. In general, there were decreasing genetic trends for AFC, fat percentage and protein percentage over the years but there were increasing genetic trends for milk yield, mature-equivalent milk yield, fat yield, mature-equivalent fat yield, protein yield and mature-equivalent protein yield over the years. On the other hand, there was a decreasing phenotypic trend for AFC but estimates of phenotypic trends were positive for milk yield and compositions over the years. It seems that the decline in calving age in this study over time resulted primarily from increased turnover rate and increased culling of heifers that failed to get pregnant. On the other hand, increasing trend for yield traits over time in this study indicated that Iranian dairy producers were successful in choosing progressively better semen and sires from imported and local sources over the years.

Genetic parameters of milk cholesterol content in Holstein cattle

2018 ◽  
Vol 98 (4) ◽  
pp. 714-722 ◽  
Author(s):  
Duy N. Do ◽  
Allison Fleming ◽  
Flavio S. Schenkel ◽  
Filippo Miglior ◽  
Xin Zhao ◽  
...  
Keyword(s):  
Milk Fat ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Cholesterol Content ◽  
Production Traits ◽  
Fat Percentage ◽  
Bivariate Models ◽  
Estimate Heritability ◽  
Fat Yield ◽  
Using Data

This study aimed to estimate heritability for milk cholesterol (CHL) and genetic correlations between milk CHL and other production traits (test-day milk, fat, and protein yields, fat and protein percentages, and somatic cell score). Milk CHL content was determined by gas chromatography and expressed as mg of CHL in 100 g of fat (CHL_fat) or in 100 mg of milk (CHL_milk). Univariate models were used to estimate variances and heritability, whereas bivariate models were used to compute correlations using data from 1793 cows. The average concentrations (standard deviation) of CHL_fat and CHL_milk were 275.63 (75) mg and 11.16 (3.63) mg, respectively. Milk CHL content was significantly affected by days in milk and herd (P < 0.05), but not by parity, regardless of the scale of expression. Heritability estimates for CHL_fat and CHL_milk were 0.06 ± 0.04 and 0.17 ± 0.06, respectively. Phenotypic and genetic correlations between CHL_fat and CHL_milk were 0.82 and 0.44 ± 0.24, respectively. CHL_fat had nonsignificant genetic correlations with all production traits, whereas CHL_milk had significant (P < 0.05) genetic correlations with milk yield (−0.47), fat yield (0.51), protein percentage (0.56), and fat percentage (0.88). This is the first study to estimate genetic parameters for milk CHL content. Further studies are required to assess the possibility of genetically selecting cows with lower milk CHL content.

scholarly journals Genetic trends for milk, fat and protein in the Zimbabwean Holstein-Friesian population from 1973 to 1994

2001 ◽  
Vol 44 (1) ◽  
pp. 23-32
Author(s):  
K. Kunaka ◽  
S. M. Makuza ◽  
C. B. A. Wollny ◽  
J. W. Banda
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Milk Fat ◽  
Selection Index ◽  
Milk Composition ◽  
Small Population ◽  
Data Sets ◽  
Data Set ◽  
Quadratic Effects ◽  
Genetic Trends

Abstract. Genetic trends based on 30 395 records with parities 1 to 8 were estimated using average information restricted maximum likelihood algorithm (AIREML), which had overall mean, herd, month of calving, year of birth, parity and linear and quadratic effects of days in milk. Due to changes in the Zimbabwean milk recording system data set was split into records of cows born from 1973 to 1989 and the other from 1987 to 1994. The first data set was further split into even numbered herds (EVNH73) and odd numbered herds (ODNH73), due to computational limitations. The highest milk production was from May to August. Peak milk production was observed in parity 4. The heritabilities for FCM (0.22 to 0.26), fat percent (0.24 to 0.28) and protein percent (0.21) were comparable to literature values. The annual genetic trends of FCM ranged from 8.36 kg to 13.2 kg, fat per cent ranged from 0.0 % to −0.008 % and protein per cent was −0.003 % in the three data sets. Genetic trends for milk yield, fat and protein yield were also positive but overally lower than in most other countries. The positive genetic trends obtained for milk, fat and protein yields imply that some progress has been made in increasing the milk production despite the relatively small population and significant restrictions. There is need to develop a selection index to improve milk yield and milk composition.

Nutritional practices on Manitoba dairy farms

2004 ◽  
Vol 84 (3) ◽  
pp. 501-509 ◽  
Author(s):  
J. C. Plaizier ◽  
T. Garner ◽  
T. Droppo ◽  
T. Whiting
Keyword(s):  
Milk Production ◽  
Milk Fat ◽  
Diet Composition ◽  
Dairy Herd ◽  
Dairy Farms ◽  
Feeding Practice ◽  
Net Energy ◽  
Fat Percentage ◽  
Penn State ◽  
Rumen Undegradable Protein

A survey was conducted on 40 randomly selected dairy farms across Manitoba to document nutritional practices and diet compositions, and study relationships between diet composition and milk production. Samples from all feeds, diets, and the bulk milk tank were collected and analyzed. Inclusion rates of feed ingredients were recorded. Production data were obtained from Western Canada Dairy Herd Improvement Services (WCDHIS). Component feeding and total mixed ration (TMR) feeding were used in 37.5 and 62.5% of herds, respectively. Only 24% of TMR-fed herds used two or more TMR. The medians of dietary contents of crude protein (CP), rumen degradable protein (RDP), rumen undegradable protein (RUP), and neutral detergent fibre (NDF), and milk urea nitrogen (MUN) were 18.3% dry matter (DM), 12.2% DM, 5.7% DM, 34.8% DM, and 15.6 mg dL-1, respectively. On average, diets contained 6.2% more net energy for lactation (NEl), 35.9% more RDP, 15.8% less RUP, 74.6% more calcium (Ca), 51.9% more phosphorous (P), 44.9% more potassium (K), 116.1% more magnesium (Mg), and 4.2% more sodium (Na) than the estimated requirements based on the average milk production and estimated DM intake of the cows on each farm. In 25% of TMR-fed herds, TMR was coarser than recommended. Milk yield, and milk fat percentage were affected by breed, but were not affected by feeding practice (TMR or component feeding), diet composition, and physically effective NDF (peNDF) determined as the percent age of feed particles retained by the 8- and 19-mm screens of the Penn State Particle Separator multiplied by dietary NDF. Milk protein percentage was positively correlated to RUP. MUN was positively correlated to RDP, RUP, NDF, and days in milk (DIM). Reductions in dietary CP, RDP, Ca, P, Mg, and K could reduce nutrient excretions to the environment without reducing milk production and health. Increasing dietary RUP content could improve milk production on Manitoba dairy farms. Key words: Dairy cattle, milk production, protein, fibre, minerals, particle size.

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