| 1. |
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| 2. |
- Emanuelson, Ulf, et al.
(författare)
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Relationship between somatic cell count and milk yield in different stages of lactation
- 2009
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 92, s. 3124-3133
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Tidskriftsartikel (refereegranskat)abstract
- The association between somatic cell count (SCC) and daily milk yield in different stages of lactation was investigated in cows free of clinical mastitis (CM). Data were recorded between 1989 and 2004 in a research herd, and consisted of weekly test-day (TD) records from 1,155 lactations of Swedish Holstein and Swedish Red cows. The main data set (data set A) containing 36,117 records excluded TD affected by CM. In this data set, the geometric mean SCC was 55,000 and 95,000 cells/mL in primiparous and multiparous cows, respectively. A subset of data set A (data set B), containing 27,753 records excluding all TD sampled in lactations affected by CM, was created to investigate the effect of subclinical mastitis (SCM) in lactations free of CM. Daily milk yields were analyzed using a mixed linear model with lactation stage; linear, quadratic and cubic regressions of log(2)-transformed and centered SCC nested within lactation stage; weeks in lactation; TD season; parity; breed; pregnancy status; year-season of calving; calving, reproductive, metabolic and claw disorders; and housing system as fixed effects. A random regression was included to further improve the modeling of the lactation curve. Primiparous and multiparous cows were analyzed separately. The magnitude of daily milk loss associated with increased SCC depended on stage of lactation and parity, and was most extensive in late lactation irrespective of parity. In data set A, daily milk loss at an SCC of 500,000 cells/mL ranged from 0.7 to 2.0 kg (3 to 9%) in primiparous cows, depending on stage of lactation. In multiparous cows, corresponding loss was 1.1 to 3.7 kg (4 to 18%). Regression coefficients of primiparous cows estimated from data set B were consistent with those obtained from data set A, whereas data set B generated more negative regression coefficients of multiparous cows suggesting a higher milk loss associated with increased SCC in lactations in which the cow did not develop CM. The 305-d milk loss in the average lactation affected with SCM was 155 kg of milk (2%) in primiparous cows and 445 kg of milk (5%) in multiparous cows. It was concluded that multiparous cows in late lactation can be expected to be responsible for the majority of the herd-level production loss caused by SCM, and that preventive measures need to focus on reducing the incidence of SCM in such cows.
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| 3. |
- Forabosco, Flavio, et al.
(författare)
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International genetic evaluation for direct longevity in dairy bulls
- 2009
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 92, s. 2338-2347
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were to document, present, and discuss the procedure used to calculate the international estimated breeding value (EBV) for longevity for Brown Swiss, Guernsey, Holstein, Jersey, Red Dairy Cattle, and Simmental breeds. Data from 19 countries and 123,833 national sires' breeding value were used for this purpose. Trait definitions and national genetic evaluation procedures were first summarized; and this showed that differences among countries existed. International breeding values for direct longevity were calculated using a multi-trait across-country evaluation model. The data editing method was identical to the one used for the February 2007 routine international genetic evaluation. Estimated genetic correlations presented in this study were similar to those presented in the literature and, in general, differed from unity because of differences in trait definitions, culling reasons, data included, evaluation procedures, genotype-environment interactions, and weak genetic ties among countries. The average genetic correlations for Holstein ranged from 0.49 to 0.76. The genetic correlations for Brown Swiss and Guernsey ranged from 0.29 to 0.95 and from 0.30 to 0.89, respectively. For Jersey and Red Dairy Cattle the genetic correlations ranged from 0.39 to 0.61 and from 0.30 to 0.96, respectively. For Simmental the genetic correlation was 0.59. Different predictors were used at national levels to define combined longevity. These predictors were combined using economic and empirical weights. Three out of 15 countries published international EBV of direct longevity only and 12 out of 15 countries combined direct longevity with predictors (combined longevity). International breeding values for longevity were combined into the total merit index by most of the member organizations and made available to breeders across the world through magazines and Web sites. Even if some breeders are not familiar with longevity EBV, they will select for this trait automatically if they use the published total merit indexes.
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| 4. |
- Freiburghaus, Catja, et al.
(författare)
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Lactoferricin treatment decreases the rate of cell proliferation of a human colon cancer cell line.
- 2009
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 1525-3198 .- 0022-0302. ; 92:6, s. 2477-2484
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Tidskriftsartikel (refereegranskat)abstract
- Food components modify the risk of cancer at a large number of sites but the mechanism of action is unknown. In the present investigation, we studied the effect of the peptide lactoferricin derived from bovine milk lactoferrin on human colon cancer CaCo-2 cells. The cells were either untreated or treated with 2.0, 0.2, or 0.02 microM lactoferricin. Cell cycle kinetics were investigated with a bromodeoxyuridine DNA flow cytometric method. The results show that lactoferricin treatment slightly but significantly prolonged the S phase of the cell cycle. Lactoferricin treatment lowered the level of cyclin E1, a protein involved in the regulation of genes required for G(1)/S transition and consequently for efficient S phase progression. The slight prolongation of the S phase resulted in a reduction of cell proliferation, which became more apparent after a long treatment time.
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| 5. |
- Glantz, Maria, et al.
(författare)
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Effects of animal selection on milk composition and processability.
- 2009
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 1525-3198 .- 0022-0302. ; 92:9, s. 4589-4603
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Tidskriftsartikel (refereegranskat)abstract
- One goal of animal breeding is to increase the economic output through increased production, improved milk quality, and cow health. The objective of this study was to evaluate genetic progress in relation to milk composition, processability, and yield as a correlated response to selection for the Swedish breeding objective. Dairy cows with high genetic merit, classified as elite dairy cows, of the Swedish Red and Swedish Holstein breeds were used. Milk samples were collected on the farm level in winter and summer from a research herd at Nötcenter Viken, a bovine research farm in Sweden. Comparisons were made with milk from a Swedish Red herd, a Swedish Holstein herd, and a Swedish dairy processor in the same geographical area. Protein, lipid, and carbohydrate profiles as well as minerals were analyzed, and technological properties, including rennet-induced gelation characteristics, lipid oxidation, total antioxidant capacity, and fat globule size, were determined. Higher yields were found for elite cows for components of the protein, lipid, and carbohydrate profiles as well as for minerals, implying genetic progress in relation to milk yield; however, the content of some milk components (e.g., lipid and whey protein contents) had decreased on average. Milk from the elite cows had good gelation characteristics, but was more susceptible to lipid autooxidation and had a lower total antioxidant capacity. These results demonstrate that milk composition and processing characteristics could be used to adjust breeding practices to optimize the quality and stability of milk and dairy products.
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| 6. |
- Hultgren, Jan, et al.
(författare)
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Lifetime risk and cost of clinical mastitis in dairy cows in relation to heifer rearing conditions in southwest Sweden
- 2009
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 92, s. 3274-3280
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Tidskriftsartikel (refereegranskat)abstract
- Relationships between heifer rearing conditions and the risk of veterinary-reported clinical mastitis (VRCM) during productive life were studied by generalized linear mixed modeling at the lactation level. Data consisted of 5,693 lactations in 2,126 Swedish Reds, Swedish Holsteins, or dairy cows of other or mixed breeds, representing all female animals born in 110 herds in southwest Sweden in 1998. During a lactation, a cow was defined as affected by VRCM if one or more cases were reported by a veterinarian, starting from 7 d pre-calving. The applied model of VRCM included effects of breed, parity, diarrhea between 3 and 7 mo of age, increase in body weight from weaning to first breeding, increase in daily concentrate ration before first calving, herd-level median age at first calving, cow housing, and random effects of cow and herd. The VRCM incidence was 14% in a given lactation, or 0.11 cases/cow annually; 31% of the cows had VRCM at least once during their productive life. Ninety percent of the variation in mastitis risk was due to factors at the lactation level such as parity, milk yield, cow diseases, and other disturbances, instead of cow or herd factors. Severe diarrhea between 3 and 7 mo of age was associated with 2.8-fold higher odds of VRCM compared with mild diarrhea during the same period, whereas the VRCM odds of calves with mild diarrhea were half that without diarrhea. The odds of VRCM had a predicted maximum at an estimated prepubertal growth rate of 859 g/d and increased with 10% for every 1-kg increase in concentrate ration during the last 2 mo before first calving. Costs of VRCM were estimated based on assumptions regarding veterinary service, extra labor, culling and herd replacement, discarded milk, and production loss depending on parity and lactation stage when VRCM was diagnosed. The total mean costs of VRCM were estimated to be $735 per lactation with a diagnosis of CM, $103 per lactation across all cows, or $95 per cow annually during lifetime.
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| 7. |
- Höglund, Johanna Karolina
(författare)
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Genome scan detects quantitative trait loci affecting female fertility traits in Danish and Swedish Holstein cattle
- 2009
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 92, s. 2136-2143
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Tidskriftsartikel (refereegranskat)abstract
- Data from the joint Nordic breeding value prediction for Danish and Swedish Holstein grandsire families were used to locate quantitative trait loci (QTL) for female fertility traits in Danish and Swedish Holstein cattle. Up to 36 Holstein grandsires with over 2,000 sons were genotyped for 416 microsatellite markers. Single trait breeding values were used for 12 traits relating to female fertility and female reproductive disorders. Data were analyzed by least squares regression analysis within and across families. Twenty-six QTL were detected on 17 different chromosomes. The best evidence was found for QTL segregating on Bos taurus chromosome (BTA) 1, BTA7, BTA10, and BTA26. On each of these chromosomes, several QTL were detected affecting more than one of the fertility traits investigated in this study. Evidence for segregation of additional QTL on BTA2, BTA9, and BTA24 was found.
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| 8. |
- Höglund, Johanna Karolina
(författare)
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Overlapping chromosomal regions for fertility traits and production traits in the Danish Holstein population
- 2009
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 92, s. 5712-5719
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Tidskriftsartikel (refereegranskat)abstract
- Before implementing selection based on quantitative trait loci (QTL) for fertility, it is important to determine the existence of correlated effects between the fertility QTL and QTL with effects on production traits. When a QTL is detected for a trait that is a composite of subtraits, it is of interest to validate which of the subtraits are affected by the QTL. Phenotypic and marker data were collected from 34 grandsire families from the Danish Holstein population. First, the trait data for "fertility treatments" were separated into their underlying subtraits: uterine infections, antibiotics placed in the placenta, and abortions. In addition, retained placenta was selected for analysis because it is related to uterine infections. A genome scan was performed using 416 microsatellite markers for the fertility treatment subtraits and retained placenta, and an additional genome scan for milk production traits conditional on the QTL regions for the subtraits and retained placenta was conducted. Second, we selected 24 genomic regions harboring QTL for fertility traits from a previous study. A QTL scan for milk production traits conditional on the selected regions was conducted. We found that 16 selected genomic regions containing a QTL for fertility (including the fertility treatment subtraits and retained placenta) also harbored QTL for milk yield or milk composition traits. Furthermore, 12 QTL regions corresponding to 9 different fertility traits (including the fertility treatment subtraits) did not harbor a QTL for milk production or milk composition traits; that is, the region was specific for the fertility trait. The genome scan for the fertility treatment subtraits did not correspond to the QTL found for fertility treatments. No QTL were detected for the subtrait abortion, however genome scans for retained placenta revealed 4 different QTL.
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| 9. |
- Näslund, J, et al.
(författare)
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Frequency and effect of the bovine acyl-CoA : diacylglycerol acyltransferase 1 (DGAT1) K232A polymorphism in Swedish dairy cattle
- 2008
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 91:5, s. 2127-2134
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Tidskriftsartikel (refereegranskat)abstract
- Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is a key enzyme in triacylglycerol synthesis in the mammary gland, and the corresponding gene has emerged as a strong candidate for the variation in milk fat percentage. In this study, the allele frequencies and effects of the DGAT1 K232A variants in the Swedish dairy breeds Swedish Red and Swedish Holstein were investigated. A total of 239 cows, 143 of the Swedish Red breed and 96 of the Swedish Holstein breed, in the experimental herd at the Swedish University of Agricultural Sciences were genotyped for the DGAT1 polymorphism. The Swedish Red cows in the herd belonged to 1 of 2 selection lines with high or low milk fat percentage, respectively, but with similar high total milk energy production. The frequency of the K variant was found to be significantly greater in the high-fat line than in the low-fat line. The average frequency of the K variant in the 2 lines of the Swedish Red cows was 0.09 compared with 0.12 among the Swedish Holstein cows. Mixed model analysis was used to estimate the effect of the DGAT1 K232A polymorphism based on 16,866 test-day records for milk production traits. In accordance with previous studies, the most pronounced effects were found for fat and protein percentages and milk yield; and the K variant was associated with an increase in milk fat and protein percentages but less milk yield compared with the A variant. Less pronounced effects were found for yields of fat and protein for which the K variant was associated with greater fat yield but less protein yield.
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| 10. |
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