Milk losses associated with somatic cell counts by parity and stage of lactation

Autor(es)

Goncalves, Juliano L. ^[1] ; Cue, Roger I. ^[2] ; Botaro, Bruno G. ^[3] ; Horst, Jose A. ^[4] ; Valloto, Altair A. ^[4] ; Santos, Marcos V. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Vet Med & Anim Sci, Dept Anim Nutr & Prod, BR-13635900 Pirassununga, SP - Brazil

^[2] McGill Univ, Dept Anim Sci, Macdonald Campus, Montreal, PQ H9X 3V9 - Canada

^[3] Teagasc, Anim & Grassland Res & Innovat Ctr, Livestock Syst Res Dept, Moorepk, Fermoy P61 C996, Co Cork - Ireland

^[4] APCBRH, BR-81200404 Curitiba, Parana - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF DAIRY SCIENCE; v. 101, n. 5, p. 4357-4366, MAY 2018.
• Citações Web of Science: 2

Resumo

The reduction of milk production caused by subclinical mastitis in dairy cows was evaluated through the regression of test-day milk yield on log-transformed somatic cell counts (LnSCC). Official test-day records (n = 1,688,054) of Holstein cows (n = 87,695) were obtained from 719 herds from January 2010 to December 2015. Editing was performed to ensure both reliability and consistency for the statistical analysis, and the final data set comprised 232,937 test-day records from 31,692 Holstein cows in 243 herds. A segmented regression was fitted to estimate the cutoff point in the LnSCC scale where milk yield started to be affected by mastitis. The statistical model used to explain daily milk yield included the effect of herd as a random effect and days in milk and LnSCC as fixed effects regressions, and analyses were performed by parity and stage of lactation. The cutoff point where milk yield starts to be affected by changes in LnSCC was estimated to be around 2.52 (the average of all estimates of approximately 12,400 cells/mL) for Holsteins cows from Brazilian herds. For first-lactation cows, milk losses per unit increase of LnSCC had estimates around 0.68 kg/d in the beginning of the lactation {[}5 to 19 d in milk (DIM)], 0.55 kg/d in mid-lactation (110 to 124 DIM), and 0.97 kg/d at the end of the lactation (289 to 304 DIM). For second-lactation cows, milk losses per unit increase of LnSCC had estimates around 1.47 kg/d in the beginning of the lactation (5 to 19 DIM), 1.09 kg/d in mid-lactation (110 to 124 DIM), and 2.45 kg/d at the end of the lactation (289 to 304 DIM). For third-lactation cows, milk losses per unit increase of LnSCC had estimates around 2.22 kg/d in the beginning of the lactation (5 to 19 DIM), 1.13 kg/d in mid-lactation (140 to 154 DIM), and 2.65 kg/d at the end of the lactation (289 to 304 DIM). Daily milk losses caused by increased LnSCC were dependent on parity and stage of lactation, and these factors should be considered when estimating losses associated with subclinical mastitis. (AU)

• Processo FAPESP: 14/17411-6 - Impacto econômico e perfil de agentes etiológicos da mastite bovina
• Beneficiário: Marcos Veiga dos Santos
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/23613-8 - Impacto da mastite subclínica sobre custo de produção e qualidade do leite em rebanhos leiteiros
• Beneficiário: Juliano Leonel Gonçalves
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 15/04570-1 - Impacto da mastite subclínica sobre custo de produção e qualidade do leite em rebanhos leiteiros
• Beneficiário: Juliano Leonel Gonçalves
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado