Effect of somatic cell count on milk fat and protein in different parities and stages of lactation in Holstein cows

Abstract

Effect of somatic cell count on milk fat and protein in different parities and stages of lactation in Holstein cowsThe objective of this study was to investigate the effect of somatic cell score (SCS) on milk fat and protein in different parities and stages of lactation in Iranian Holstein cows. Records between June 2003 and January 2014 from 208,478 cows in lactations one to nine in 845 herds, comprising 2,456,303 monthly test-day (TD) records were used. The MIXED procedure of the SAS software with repeated measurements was used. The fixed effects of the model were herd, year-season of calving, month of TD, weeks of lactation, previous dry period length and somatic cell score (SCS) and covariate was calving age. Lactations were divided into six stages and analyses were performed within each stage. Also, different lactations were analyzed separately. Increase of SCS led to increase of milk fat and protein percentage and the increase of milk fat and protein associated with SCS was higher in early stages of lactation relative to later stages of lactation. Also, increase of milk fat and protein associated with SCS was higher in the first lactation rather than later lactations and decreased with increase of parity.Key words: cattle; dairy cows; breeds; Holstein; milk; proteins; fat; somatic cell score; lactation; Iran Vpliv števila somatskih celic na odstotek maščobe in beljakovin v mleku holštajnskih krav v različnih zaporednih laktacijah in v različnih stadijih laktacijeNamen te raziskave je bil proučiti učinek števila somatskih celic (SCS) na vsebnost mlečne maščobe in beljakovin v različ-nih laktacijah in v različnih fazah laktacije pri iranskih kravah holštajnske pasme. Uporablili smo podatke za 208.478 krav v prvi do deveti laktaciji iz 845 čred, ki so vsebovali 2.456.303 zapisov za mesečni testni dan (TD). Analiza je bila opravljena s proceduro MIXED s ponovljenimi meritvami v programskem paketu SAS. Fiksni vplivi v modelu so bili čreda, leto-sezona telitve, mesec testnega dneva, teden laktacije, trajanje predhodne presušitve in število somatskih celic ter starost ob telitvi kot kovariabla. Laktacije smo razdelili v šest obdobij in opravili analize znotraj vsakega obdobja. Analize so bile opravljene ločeno po laktacijah. Povečanje števila somatskih celic je vodilo do povečanja odstotka maščob in beljakovin, ki je bilo večje v zgodnjih obdobjih laktacije v primerjavi s kasnejšimi. Povečanje vsebnosti maščob in beljakovin je bilo tudi večje v prvi laktaciji kot v kasnejših laktacijah in je upadalo z zaporedno laktacijo.

Mastitis, somatic cell count and milk quality: an overview

“…Sharma et al(2011) and Bharti et al (2017) reported that there was a positive correlation between SCC and parity, which is attributed to epithelial damage and prevailing pathogen with repeated infections. Also, Sharma et al(2011) and Chegini et al(2016) reported that SCC is high in the late lactation than the early lactation which has been explained as being due to the dilation of the teat canal. A seasonal variation in SCC has been observed, being higher in cows calved in summer than that of winter (Bharti et al, 2017, andBaul et al, 2011).…”

Productive and reproductive performance of Holstein cows in Agreste, Pernambuco, from 2007 to 2017

“…Other factors that can influence milk productivity and quality, in addition to environmental factors, are physiological factors, such as age at first calving, birth order and lactation period (Chegini, Ghavi, Hosseini, & Shadparvar, 2017). The changes that occur with the advancement of age are mainly caused by physiological factors and lead to maximum performance at maturity followed by a decrease as the animal ages, an effect that is directly related to the order of calving (Soares, Rangel, Aguiar, Medeiros, & Lima, 2009).…”

Selection of dairy cattle for mastitis resistance by somatic milk cells as a system of biological protection against lacteous gland diseases

“…In recent years, the role of genetic factors in reducing the frequency of mastitis (udder inflammation) in cows, a widespread and dangerous disease, has been actively investigated [1][2][3][4]. When organizing the screening and selection of dairy cattle for mastitis resistance, the frequency of the disease in herds and populations is considered, as well as an indirect sign associated with mastitis -the number of somatic cells in milk (NSC) [5][6][7].…”