Genetic relationship between milk dry matter and other milk traits in extended lactations of Polish Holstein cows

Abstract

Random regression models (RRM) have recently been used not only in the analysis of milk traits such as milk, fat and protein yield, but also somatic cell score (SCS), lactose yield and milk urea nitrogen (MUN), and very seldom they have been applied to analyze milk dry matter (DM) yield. RRM have many advantages over lactation models: 1) they account more accurately for environmental factors affecting the performance of cows in each day in milk (DIM) throughout the lactation, 2) they allow ABSTRACT: The objective of this research was to examine heritabilities and genetic, phenotypic and permanent environmental relationships between milk dry matter (DM) and milk traits such as milk, fat, protein and lactose yields, milk urea nitrogen (MUN) and somatic cell score (SCS) in extended (to 395 days) lactations of Holstein cows from a big farm in Poland. The data set consisted of 78 059 test day records from the first, second and third lactations of 3 792 cows, daughters of 210 sires and 1 677 dams. Single-or two-trait random regression models were used with fixed effects of calving year, calving month, dry period and calving interval and random additive genetic and permanent environmental effects. The last two fixed effects were not included in the analysis of first lactation data. The highest values of heritabilities for all traits, except DM, were observed in the second lactation. First lactation heritabilities for all traits -except milk yield and SCS -were smaller than those in the third lactation. Lactose yield was highly heritable, with average h 2 equal to 0.25, 0.29 and 0.28 in lactations 1, 2 and 3, respectively. Heritability for DM was slightly lower than that for lactose (0.22, 0.26 and 0.28 for lactations 1, 2 and 3, respectively). In all lactations heritabilities for SCS were below 0.1. Genetic correlations between DM and milk yield (0.64-0.74) were lower than those between MUN and milk yield (0.67-0.79) as well as between lactose and milk yield (0.72-0.82). In general, DM was much more closely correlated with fat or protein yield (0.55-0.79) than with MUN or lactose (0.38-0.76). Only in the third lactation the correlation between DM and protein (0.72) was lower than between lactose and protein (0.76). For all lactations there were very high genetic correlations between DM and lactose (0.96-0.98) and high correlations between ) and between lactose and MUN (0.70-0.85). The results suggest that further research is needed, focused on DM and its relationship with other traits in larger populations.

Genetic parameters for somatic cell score in the first three lactations of Czech Holstein and Fleckvieh breeds using a random regression model

“…On the other hand, DeGroot et al (2007) and Yazgan et al (2010) reported very low heritability estimates. DeGroot et al (2007) explained the low values by the fact that they used a high percentage of non-registered (grade) cows in the analysis.…”

Asociación del valor genético del toro con caracteres productivos en vacas lecheras en Colombia

“…Estas frecuencias confirman la inferioridad de los valores genéticos estimados ya que muestran una alta frecuencia de los rangos más bajos para producción de leche. La heredabilidad obtenida para producción de leche para las razas Holstein y Jersey, fue inferior a la reportada por Ojango y Pollott (2001) y Yazgan et al (2010). En el caso del porcentaje de grasa y proteína las heredabilidades encontradas en esta investigación para la raza Holstein son muy inferiores a las reportadas por otros autores, pero similares a las encontradas en la raza Jersey (Juga, 1992;Hashemi et al, 2009 C1= 007HO05708; C2= 072HO00753; C3= 073HO02479; C4= 029HO08246; C5= 073HO01965; C6= 009HO01895; C7= NAL012HO; C8= 072HO00753; C9= NAL068HO; C10= 220HO09600; C11= 001JE01325; C12= 014JE00365; C13= NAL0525ACCGJ; C14= 014JE00285; C15= 007JE00535; C16= 014JE00326; C17= 014JE00205; C18= 007JE00622; C19= 007JE00535; C20= 071JE00162.…”

“…Las heredabilidades estimadas para el recuento de células somáticas en ambas razas, es muy superior a las reportadas por otros autores (Yazgan , 2010).…”

Estimation of genetic parameters and evaluation of test-day milk production in sheep

“…Presently, it is common to evaluate milk yield and dry matter production in cows using a random regression model (Yazgan et al, 2010). This procedure has also been successfully applied to milk production in sheep (Horstick et al, 2002).…”