Effect of somatic cell count and mastitis pathogens on milk composition in Gyr cows

BMC Veterinary Research

Table 1 Final mixed linear regression models of the effect of seasonality, mastitis-causing pathogens and somatic cell count on milk composition at the mammary quarter level in Gyr cows ¹

	Lactose, %			Protein, %			Fat, %			Nonfat solids, %			Total solids, %
Fixed effects	β	SE	P-value	β	SE	P-value	β	SE	P-value	β	SE	P-value	β	SE	P-value
Intercept	4.660	0.081		3.662	0.087		1.689	0.335		9.295	0.098		11.004	0.427
Seasonality²
Dry	Ref.	…	…	Ref.	…	…	Ref.	…	…	Ref.	…	…	Ref.	…	…
Rainy	0.105	0.015	<.0001	−0.322	0.012	<.0001	−0.208	0.039	<.0001	−0.222	0.018	<.0001	−0.437	0.044	<.0001
IMI³
Negative	Ref.	…	…	Ref.	…	…	Ref.	…	…	Ref.	…	…	Ref.	…	…
S. aureus	−0.041	0.024	0.089	−0.044	0.019	0.023	−0.082	0.062	0.183	−0.091	0.029	0.002	−0.191	0.071	0.007
CNS⁴	−0.023	0.022	0.294	−0.033	0.018	0.062	−0.175	0.057	0.002	−0.063	0.027	0.017	−0.241	0.065	0.0002
CORY⁵	−0.082	0.021	0.0002	0.052	0.017	0.003	−0.138	0.055	0.012	−0.015	0.025	0.554	−0.161	0.063	0.010
STREP⁵	−0.062	0.037	0.092	−0.031	0.029	0.297	−0.232	0.095	0.014	−0.099	0.044	0.023	−0.346	0.107	0.001
SCC⁶	−0.0002	0.00004	<.0001	0.00005	0.00004	<.0001	0.0002	0.00001	<.0001	−0.0002	0.00005	<.0001	0.00005	0.00002	<.0001

¹ A total of 3,203 observations were used in this analysis. ²Seasonality (1 = rainy season, October to March; 0 = dry season, April to September), ³ IMI: intramammary infection; ⁴CNS: coagulase negative staphylococci, ⁵ CORY: Corynebacterium spp., ⁶ STREP: Streptococcus sp. (S. uberis, S. agalactiae, S. dysgalactiae), ⁶ SCC: somatic cell count (x 1000 cells/mL), β: estimated coefficients, SE: standard error for the coefficient, Ref.: reference.

ISSN: 1746-6148