Banca de DEFESA: PAMELA ASSIS GELIER

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : PAMELA ASSIS GELIER
DATE: 30/06/2021
TIME: 14:00
LOCAL: INSTITUTO DE ZOOTECNIA
TITLE:

Effect of season of year, production level and mastitis causative agent on milk quality in semi-intensive production systems.

KEY WORDS:

SCC, SPC, fat, protein, variation, microbiological culture.

PAGES: 58
BIG AREA: Ciências Agrárias
AREA: Zootecnia
SUBÁREA: Produção Animal
SUMMARY:

GELIER, Pamela Assis. Effect of season of year, production level and mastitis causative agent on milk quality in semi-intensive production systems. 2021. 57p. Dissertation (Masters in Animal Science, Animal Production). Institute of Animal Science, Department of Animal Production, Federal Rural University of Rio de Janeiro, Seropédica, RJ, 2021. Dairy farming is growing with a high demand for quality products. With this, the search for research and tools that collaborate in improving the quality of milk in dairy properties is notorious every day. In this context, two studies were carried out with the aim of evaluating the influence of some factors on the composition and quality of milk. In study I, the objective was to evaluate the influence of time of year and level of production on milk composition, as well as levels of urea nitrogen (NUL), CCS (Somatic cell count) and CPP (Standard plate count). The study was conducted with data from 470 dairy farms located in the region of Vale do Paraíba-SP, the data collection period took place from September 2016 to August 2019. The farms were classified according to production daily average of milk, at three levels of production: 1) High; 2) Medium; and 3) Low. Weekly collections were taken from the pool of each farm's tank to analyze the chemical composition of the milk, CCS and CPP. The study analyzed according to a mixed model where the variables of interest (time of the year and production volume) were considered as a fixed effect in the statistical model, while the farm and year effects were included as random effects in the model. The time of year interfered in CPP, CCS and in all indices of milk composition, presenting the best patterns in the driest months of the year, also a period of greater supplementation of the animals. The level of production interfered in CPP, CCS and NUL, where low production farms have lower levels of NUL and CCS than medium and high production farms. The CPP increased when the farm's production level decreased. In study II, the objective was to evaluate the interference of production level, season of the year, lactation month and type of pathogen present on CCS. The study was carried out with data from 42 dairy farms located in the region of Vale do Paraíba-SP. Farms were also classified, according to the average daily milk production, into three production levels. Individual milk collections were performed monthly for CCS analysis and biannual individual collections for microbiological culture. The study was analyzed in a mixed model where the variables of interest (eg month of the year, production level and the type of pathogen) were considered as a fixed effect in the statistical model, while the farm and year effects were included as random effects. in the model. The month of the year interfered in CCS, presenting the highest averages from February to August. The lactation month interfered in the CCS, showing a linear growth as the lactation period increases. There was an individual effect of the pathogen causing mastitis on CCS, animals that showed positive microbial culture for S. aur and S. aga, had higher levels of CCS, animals that showed positive microbial culture for the groups of agents C. bov, E. spp, S. neg and S. ssp, had lower CCS values and animals positive for the Other agents group had CCS values below 200×103 cel/mL. Using the Low production level as a reference, there was a lower occurrence of the agent S. aur at the High and Medium production levels and a higher occurrence of the agent S. aga and the agent S. neg at the High production levels. It was concluded that the seasons of the year interfere in all milk composition indexes and the farm's production level interferes in the NUL and CPP contents. The month of lactation and the causative agent of mastitis interfere with the individual CCS.

BANKING MEMBERS:
Externo à Instituição - TADEU ÉDER DA SILVA
Presidente - 3055881 - ALEX LOPES DA SILVA
Externo à Instituição - JOSÉ CARLOS DE FIGUEIREDO PANTOJA - UNESP