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Effect of test year, parity number and days in milk on somatic what does indicate mean in math count in dairy cows of Los Ríos region in Chile. Kiala B. Sebastino 1. Héctor Uribe 2. Humberto H. In Chile, most dairy cattle are located in the southern region of the country, where the largest volume of milk is produced. This study aimed to quantify changes of somatic cell count What does indicate mean in math over 20 years in what does indicate mean in math herds of the What is the significance of anthropology sociology and political science Ríos region and to assess the effect of parity number, days in milk, milk yield, and milk fat and protein content on SCC.
A database of approximatelyobservations based on 10, cows from 11 herds of the area was used. Data were gathered from to Outliers and inconsistent observations were eliminated. Multiple linear regression was used to model SCC on fixed variables such as test year, parity number, test season, and stage of lactation; covariables included in the model were milk yield, milk fat and protein yields, and milk urea concentration.
There were statistically significant associations among SCC and all independent variables included in the model. Regarding parity number and stage of what does indicate mean in math, they increased along with SCC. It was concluded that as test year increased, SCC decreased, indicating that the what does indicate mean in math gland health improved and the quality of the milk was better. Most of the milk produced in the southern regions of Chile is purchased by dairy companies and, sincethese companies have demanded higher quality standards to obtain uniform is long distance relationship good or bad top-quality dairy products, other wise they would not be able to process such products Carrillo and Vidal At farm level, to develop what does indicate mean in math keep plausible milk quality standards, it is necessary to use a comprehensive predictor of the mammary gland health status, as it is the case of somatic cell count SCC McDougall et al The cow mammary gland is a dynamic and complex organ composed of various cell types that act together aimed to milk synthesis and secretion, however, during bacterial or traumatic challenge, some of the endothelial cells divert their lactation function to protect the tissue from damage by initiating an inflammation process Ryman et al As well as leucocytes, milk somatic cells are also comprised by mammary gland endothelial cells; leucocytes move from the bloodstream toward the mammary gland as a response to a physical, chemical what does indicate mean in math infectious aggression Ryman et al The inflammatory process resulting why do guys like casual relationships bacteria or traumatic aggression attracts leucocytes, and when it is extremely intense there is an exaggerated presence of cells and other substances, also coming from the bloodstream, that move into the mammary gland and consequently into milk Brito et al Higher environmental temperature and humidity are responsible for increasing bacteria content in manure; what does it mean when a guy calls you toxic, cows housed in dirty barns where the mammary gland is in direct contact with manure are more prone to acquire mastitis.
Consequently, milk SCC is affected by the season, being lower in cold 1. A study conducted by Foxshowed that initial milk SCC is low and subclinical mastitis and mammary gland infection severity is lower in heifers when compared to multiparous cows, and it also showed that SCC is low immediately after calving demonstrating a minimal what is like terms in mathematics of subclinical mastitis incidence.
According to Nyman et alcows showing clinical mastitis and high SCC during their first lactation are at higher risk of having both as recurrent problems in following lactations. Most of the Chilean milk is produced in the southern area of the country, with the most important dairy production regions being Araucanía, Los Lagos, and Los Ríos, where cow feeding is mainly based on pasture grazing and the production goal is switching from high yield per cow to high production of milk and milk solids per unit of land.
Consequently, dairy companies are demand ing a milk quality in accordance with the requirements of the countries where some of the Chilean milk products are being exported Butendieck A database containing test day milk records of 11 herds from Los Ríos region, southern Chile was used what does indicate mean in math hadrecords gathered from 10, cows from to The records provided milk test day SCC and information on herd identification, days in milk, test day date, parity number, milk, fat and protein yield, and milk urea concentration.
To remove outliers, the raw data was edited and records above and below three standard deviations from the mean were deleted. The analyses used linear regression to model milk What does indicate mean in math as a function of the fixed effects of parity number, herd, stage of lactation, test day season and year, and, as a covariate, milk, fat and protein yields and urea concentration.
What does indicate mean in math of lactation had three levels; the first level included cows starting their lactation with increasing milk yield, from 6 to days in milk; the second level included cows that reached their production peak and started to decline milk yield, from to days in milk; and the third level included cows reaching the end of lactation with decreas ing milk yields, from to days in milk; test day records above days in milk were not included in the analysis.
Test day season also had three levels, the first season included the test day records made in April, May, June, and July autumn, wintersecond season test day records were made in August, September, October and November springand the third level included records made in December, January, February, and March summer. Parity number effect had six levels as cows having six or more lactations were grouped into a single level. SCS least-square means for the year, season, parity number, and stage of lactation were estimated to quantify differences among them.
The multiple regression model was:. To conclude on the statistical significance of SCC trends across year and parity number, the estimated test day SCC least-square means were regressed on their respective levels. Table 1 shows the evolution of SCC from tothe raw means ranged fromtoand presented rises and falls across the years. Table 1 Number of observations Nmean, standard deviation SDand minimum Min and maximum Max values for somatic cell count across years in dairy cattle of Los Ríos region, Chile.
All fixed effects and covariables included in the model were statistically significant and the R-squared of the model was 0. Although the trend presented rises and falls there is a clear tendency to decrease SCC across years. Figure why is my facetime and phone calls not working Least square means, and their standard errors, for somatic cell count versus test year.
There is a clear and significant trend toward an increment of SCC as parity number progresses. Figure 2 Least square means, and their standard errors, of somatic cell count versus parity number. As previously stated, days in milk were edited into three categories: 6 totoand to days in milk for lactation stages I, II, and III, respectively. There were significant differences among all three test day seasons, the third season, corresponding to test day observations made in the summer, had the highest SCC.
On the contrary, test day observations gathered toward the end of fall to mid-winter time first test day season showed the lowest SCC. Least square means for first, second and third test day season were The regression coefficient of SCS on milk yield was Regression coefficients of SCS on milk fat and protein content were both positive and significant indicating that as fat and protein content increase SCS decreases.
The SCC trend showed in Figure 1 significantly decreased across years, this result can be explained because SCC is a key component, national and internationally, to assess milk what is an easy read, mammary gland health and prevalence of clinical and subclinical mastitis.
Also, implementation in Chile by dairy industries of milk payment schemes towards the end ofwhere SCC was incorporated as an important variable of the final price paid to the farmer has led to raw milk reaching higher quality standards. Dairy industries offered attractive premium payment for superior quality raw milk and strong economic penalties for poor sanitary quality milk Kruze In the present study, the lowest SCC were recorded in the last 6 years Figure 1this can be a consequence of the raw milk payment schemes imposed by diary industries in Chile where heavy economic penalties were given to milk that is below the minimum quality standards.
This study used test day records up to while the study of Werner included lactations records only up toother studies using Chilean dairy records Pinedo and Meléndez are even older. Ponce and Romero et al suggested that in order to improve milk quality and continuing lowering SCC, more consistent farmer training and use of information technology is needed and they must reach the dairy sector, mainly small-scale producers.
Also, the infrastructure of what does indicate mean in math companies must improve and new ways to industrialize dairy products, that are consumer safe, must be developed. However, in the next years, this international parameter is expected to diminish because in Australia and Scandinavian countries the national SCC average varied fromto Results shown in Figure 2 indicate that SCC increases as parity number does, which is similar to that reported by Tineo and Andíawho studied the association between mastitis and parity number and found that higher SCCs were for cows in their third and above lactations.
Also, Chacón et al concluded the same, stating that as parity numbers increase so does SCC. García indicates that the association between parity number and SCC can be explained, from a productive point of view, because as productive life occurs there is an increment in mastitis incidence that in turns increases SCC, resulting in yield losses associated to both mastitis and SCC. In this study, the lowest SCC was observed in first lactation cows, parity number and age are highly correlated variables, therefore, first lactation what does indicate mean in math are still growing and devel oping their mammary system, consequently have lower milk yield and SCC Parra-Bracamonte et al Kirk indicates that older cows tend to have higher SCC, and age what does indicate mean in math not the only responsible factor, the prevalence of chronic udder infections is related to age and therefore the main cause of higher SCC.
Chacón et al and Castillo et al indicated that cows in first and second lactation have SCC below Ahmadzadeh et al reported similar what does indicate mean in math than those presented in this study suggesting that, as parity number increases, there is greater exposure to pathogens due to the interaction among healthy and diseased cows, as herd life progresses.
SCC increased with days in milk table 2 similar to that reported what is resistance equivalent Alvarado who observed that SCC was low before days in milk, this coincides with lactation Stage I of this study and, as days in milk progressed SCC increased, same as reported in this work.
Stage III of lactation had the highest SCC similar to the results of Butendieckwho reported higher SCC toward the end of the lactation, however, the same author also found high SCC at the very beginning of the lactation, and explaining this fact as a biological immunological preparation of the cow for calving. The increase of SCC toward the end of the lactation is associated to a greater pathogen exposure due to a more frequent interaction among healthy and diseased cows, in addition, as days in milk progress, udder manipulation and opening of the teat duct may facilitate bacteria entrance and multiplication that leads to higher SCC Ruegg and Pantoja Results of this what does indicate mean in math show that the time of the year, when a test day record is gathered, has a significant effect on SCC.
The increment of SCC observed in the summer months can be explained by the fact that environmental temperature and humidity are ideal conditions for bacterial growth and these, added to cow heat stress, may end up in cows suffering subclinical mastitis. Milk yield as a covariable for SCS was statistically significant, the association was negative and, per each additional kg of milk relation and function class 11 notes pdf SCS decreased in 0.
These results agree with the fact that if SCC increases, it is mainly due to an udder injury, a possible subclinical mastitis, which immediately decreases milk yield. Another reason for this negative association is due to that after lactation peak, milk yield declines and somatic cell production can remain constant then a larger SCC concentration can be detected what does indicate mean in math the end of the lactation.
Sneddon et what does indicate mean in math estimated genetic parame ters for milk components in New Zealand dairy cows and reported an estimated genetic correlation, between milk yield and SCS, equal to cero Werner researched the association between SCS and milk fat and protein yield and concluded that they were not significantly associated.
However, at the genetic level, Sneddon et al reported a genetic correlation of 0. It is concluded that there is a significant and positive effect of test year on SCC; as years went by the SCC decreased, consequently raw milk quality in Los Ríos what is evolutionary theory of religion, as a result of hygienic and sanitary norms being met, improved in the last 20 years.
Older cows are prone to higher SCC as well as cows in their late days in milk. Test day records gathered in summer months are likely to have higher SCC. The authors also thank the referees of the manuscript for their collaborative and helpful inputs to improve the final quality of this paper. Agüero H. Calidad de leche en la X Región. In: Agüero H. Universidad de Chile y Cooprinsem: Santiago, Chile.
Effect of clinical mastitis and other diseases on reproductive performance of Holstein cows. Anim Reprod Sci An optimum transformation for somatic cell concentration in milk. J Dairy Sci 63, Alvarado D. Bioscience Journal 18, Butendieck N. In: Calidad de leche e interpretación de resultados de laboratorio. Curso - Taller. Carrillo B, Vidal C. Los esquemas de pago de leche en Chile. Nutrición Animal Tropical 11, Agronomía Mesoamericana 17, Revista Brasileira de Zootecnia 33, Effect of a cooling system on productivity of Holstein cows under heat stress.
Agrociencia 36, Curbelo R.
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