Milk yield and reproductive performance of brucellosis-vaccinated but seropositive Holstein cows

Abstract

The aim of this research was to study if seropositivity for brucellosis in vaccinated cows against this disease hampers reproductive performance and milk production in high-yielding Holstein cows. For this purpose 1,026 healthy cows and 372 cows seropositive for brucellosis were enrolled in this study. Cows positive to card test and subsequently to the rivanol test were further subjected to the radial immunodiffusion (RID) test. It was found that only 11% of the presumably infected cows by brucellosis screening tests were really infected with this disease. The reproductive performance of the group of cows with 11% Brucella-infected animals was not impaired; overall pregnancy rate did not differ between seropositive and healthy cows (30.9 vs. 29.6%). The abortion rates were similar between seropositive cows (5.3%) and seronegative animals (6.9%). Cows in the herd with 11% Brucella-infected animals produced significantly more milk than unaffected cows over a 305-day lactation (10,684 ± 1,720 vs. 10,345 ± 1,736; mean ± SD; P < 0.05). It was concluded that in dairy herds vaccinated against brucellosis with both 19 and RB51 strains, supplemental tests such as RID need to be conducted on all reactors in order to maintain diagnostic accuracy. These results also indicate that 11% animal prevalence of brucellosis did not exert a detrimental effect on 305-day milk yield and reproductive performance in high milk-yielding Holstein cows.

Risk factors associated with testing positive for brucellosis and occurrence of abortion in high-yielding Holstein heifers

“…The observed seroprevalence of bTB in brucellosis-vaccinated cows in this herd was above the maximum 26% reported data in Holstein herds with high bBR prevalence in the same zone where the current study took place (Mellado et al 2014). Despite the existence of a program to control this disease in this large dairy basin, the value of RB51 whole-herd vaccination, in combination with test-and-slaughter in controlling bovine brucellosis, has not been demonstrated.…”

“…However, most cows are asymptomatic, having this hidden infection without displaying clinical signs; thus, contributing to the spread of the illness in the herd. bBR seroprevalence in intensive dairy herds in Mexico is 23 to 35% (Mellado et al 2014), which constitutes a risk to public health and an economic hampering for intensive dairy operations. Even though the abundant resources and efforts for some decades of intensive dairy enterprises in Mexico for controlling bBR, this chronic disease is still widespread in this country (Luna-Martínez and Mejía-Terán 2002).…”

Importance of brucellosis control programs of livestock on the improvement of one health

“…Furthermore, there were lower retained placentas with healthier cows that improve the productivity of the dairy cattle. Another investigation also reported that there were no milk losses due to brucellosis in dairy Holstein herds vaccinated with both RB51 and S19 strains (Mellado et al 2014). In vaccinated herds, it is suggested to use supplemental tests like radial immunodiffusion, beside conventional card and Rivanol tests, in order to maintain the accuracy of diagnostic serological tests (Mellado et al 2014).…”

“…Another investigation also reported that there were no milk losses due to brucellosis in dairy Holstein herds vaccinated with both RB51 and S19 strains (Mellado et al 2014). In vaccinated herds, it is suggested to use supplemental tests like radial immunodiffusion, beside conventional card and Rivanol tests, in order to maintain the accuracy of diagnostic serological tests (Mellado et al 2014). Furthermore, the cattle vaccination strategy should be reevaluated in Brucella-endemic settings where mixed cattle flocks and small ruminant predominate (Beauvais et al 2016).…”

“…Apart from well-known endemic regions, brucellosis remains a neglected disease in many areas worldwide which can lead to serious health and economic concern for the livestock populations by affecting animals such as cattle, buffalo, camel, sheep and goat (Bamaiyi 2015;Mableson et al 2014;Santos et al 2013;Singh et al 2015;Sulima and Venkataraman 2010). Economic losses of brucellosis for the livestock industry and small-scale livestock holders are usually due to infertility in both sexes and late term abortion (Angara et al 2016;Awah-Ndukum et al 2018;Deka et al 2018;Franc et al 2018;Sulima and Venkataraman 2010), decreased milk yield (Herrera et al 2008;Mellado et al 2014), decreased productivity, loss in market value of animals, lost draught power, missed reproductive cycles, birth of weak offspring with low birth weight, and increased veterinary costs in farms (Blasco and Molina-Flores 2011;Dadar et al 2020a). In the cows, the disease leads to an abortion once in their lifetime and the infection is asymptomatic in non-pregnant animals which may remain infected their entire life (Godfroid et al 2010).…”