Effect of using internal teat sealant with or without antibiotic therapy at dry-off on subsequent somatic cell count and milk production

Abstract

The objective of this study was to assess the effect of treating cows with teat sealant only compared with antibiotic plus teat sealant at drying off on weekly somatic cell count, potential intramammary infection, and milk production across the entire subsequent lactation. In 3 research herds in the south of Ireland, cows with SCC that did not exceed 200,000 cells/mL in the previous lactation (LowSCC) were randomly assigned to 1 of 2 treatments at drying off: internal teat sealant alone (ITS) or antibiotic plus teat sealant (AB+ITS). Cows with SCC that exceeded 200,000 cells/mL in the previous lactation were treated with AB+ITS and included in the analyses as a separate group (HighSCC). Weekly individual animal composite SCC records were available for 654 cow lactations and were transformed to somatic cell scores (SCS) for the purpose of analysis. Data were divided into 3 data sets to represent records obtained (1) up to 35 DIM, (2) up to 120 DIM, and (3) across the lactation. Foremilk secretions were taken from all quarters at drying off, at calving, 2 wk after calving, and in mid-lactation and were cultured to detect the presence of bacteria. The LowSCC cows treated with ITS alone had higher daily milk yield (0.67 kg/d) across lactation compared with LowSCC cows treated with AB+ITS. The LowSCC cows treated with ITS alone had higher SCS in early, up to mid, and across lactation compared with LowSCC cows treated with AB+ITS. We detected no difference in weekly SCS of LowSCC cows treated with ITS alone and SCS of HighSCC cows. The least squares means back-transformed SCC across lactation of the LowSCC cows treated with ITS alone, LowSCC cows treated with AB+ITS, and HighSCC cows were 41,523, 34,001, and 38,939 cells/mL respectively. The odds of LowSCC cows treated with ITS alone having bacteria present in their foremilk across lactation was 2.7 (95% confidence interval: 1.91 to 3.85) and 1.6 (1.22 to 2.03) times the odds of LowSCC cows treated with AB+ITS and of HighSCC cows treated with AB+ITS, respectively. In this study, Staphylococcus aureus was the most prevalent pathogen isolated from the population. Recategorizing the threshold for LowSCC cows as ≤150,000 cells/mL or ≤100,000 cells/mL in the previous lactation had no effect on the results. The results indicate that herds with good mastitis control programs may use ITS alone at dry-off in cows with SCC <200,000 cells/mL across lactation with only a small effect on herd SCC.

Internal Teat Sealant Administered at Drying off Reduces Intramammary Infections during the Dry and Early Lactation Periods of Dairy Cows

“…The risk of NIMI during the dry period is increased when there is a non-or malformation of the keratin plug in the teat canals, which acts as a physical barrier against microorganisms [6,7]. However, the production of this keratin plug varies between cows [8]; 23.4% of the mammary quarter (MQ) remain open until six weeks after drying off [9], whereas 5% have no plug during the whole dry period [10].…”

>b<Eficácia do selante interno de tetos na secagem de vacas leiteiras sobre a saúde do úbere>/b<

“…As alterações que acontecem na GM durante a involução, tais como: a) volume de leite acumulado após interrupção da ordenha (PONCHON et al, 2017); b) volume de colostro acumulado próximo ao parto; c) aumento da pressão intramamária (SORDILLO; NICKERSON, 1988); d) redução da atividade das células de defesa (PAAPE et al, 2003); e e) ausência de formação do tampão de queratina (MCPARLAND et al, 2019…”

“…Após a secagem, forma-se um tampão de queratina muco-gorduroso nos canais dos tetos, o qual atua como barreira física e bacteriostática à invasão microbiana da GM (DINGWELL et al, 2004;MCPARLAND et al, 2019). No entanto, a capacidade de produção do tampão de queratina varia entre as vacas (MOLINA et al, 2017 HILLERTON, 2002;KABERA et al, 2018).…”

“…O risco de NIIM durante o PS está relacionado com a capacidade de formação do tampão de queratina muco-gorduroso nos canais dos tetos que atua como barreira física contra a invasão microbiana na GM (DINGWELL et al, 2004;MCPARLAND et al, 2019). No entanto, a capacidade de produção deste tampão é variável entre as vacas (MOLINA et al, 2017), sendo que, 23% dos quartos mamários podem permanecer abertos por até seis semanas após a secagem (DINGWELL; KELTON;LESLIE, 2003) e 5% dos quartos mamários não apresentam tampão durante todo PS (WILLIAMSON; WOOLFORD; DAY, 1995).…”

“…Neste período, a GM torna-se totalmente involuída, sendo os principais constituintes do leite presentes em concentrações muito reduzidasKITCHEN et al, 1980;BARTH et al, 2010). No entanto, apresar desta relação, estudo recente observou que a CCS apresentou maior eficácia na detecção de IIM em vacas em comparação com a Lactato desidrogenase (LDH) e NAGase (NYMAN; EMANUELSON; WALLER, 2016).Durante o período de involução completa a GM apresenta alta resistência às NIIM (Figura 1; BRADLEY; GREEN, 2004), principalmente devido à formação completa do tampão de queratina que constitui uma barreira física natural dos canais dos tetos da vaca(DINGWELL et al, 2004;MCPARLAND et al, 2019). Este tampão é uma barreira mucogordurosa que oclui o canal do teto durante o PS, visto que há diminuição da área e espessura das células epiteliais viáveis (extrato granuloso) e aumento das células epiteliais cornificadas, originando uma camada espessa de queratina(COMALLI et al, 1984).…”