ABSTRACT The objective of this study was to evaluate milk quality for somatic cell count (SCC) analysis and total bacterial count (TBC) in agroecological production systems and conventional systems, relating them to the frequency of milking practices and types of facilities. The study was conducted in 2013 and 2014, in the western region of Paraná State, Brazil. We used a semi-structured questionnaire to identify management practices of producers in the 17 dairy systems (DS) in the city of Diamante d'Oeste and the 27 DS in Toledo. Milk sampling was performed monthly. Data were analyzed using two statistical methods. These were then used to create cross tabulation of groups with production systems and practices that can influence product quality. Cluster classification analysis allowed grouping of the initial 44 production systems into three homogeneous groups: Group 1, with better quality regarding the normative instruction 62 (NI62), with average values of SCC 407.37 (cells × 1000/mL) and TBC 210.50 (cfu × 1000/mL); Group 2, with SCC 328.50 (cells × 1000/mL) and TBC 699.75 (cfu × 1000/mL), both outside the NI62 parameters; and Group 3, with SCC 680.25 (cells × 1000/mL), considered low- and high-value TBC 1775.25 (cfu × 1000/mL), out of NI62. The results indicate that management practices and some other preventions adopted during milking are the determining factors of milk quality. Therefore, SCC and TBC levels are not determined by agroecological or conventional production systems, but rather, these levels are determined by the practices differentially adopted by the production systems.

ABSTRACT The objective of the study was to evaluate the replacement of Tifton 85 hay (TH) for Tifton 85 silage (TS) in the diets of lactating cows. Five Holstein cows in middle of lactation were allocated in a 5 × 5 Latin square design and each experimental period lasted 18 days (12 days for adaptation and six days for collection). Treatments consisted of replacement of 0, 25, 50, 75, and 100% of TH for TS. The intake and digestion of nutrients, microbial protein synthesis, milk yield and composition, and the economic viability of the diets were evaluated. The intakes of dry matter, organic matter, and ether extract had a positive linear effect and the digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, acid detergent fiber decreased linearly with increasing participation of TS. Milk production and composition and microbial protein synthesis were not affected. Regarding economic viability, the treatment with 100% hay produced better results, with better gross margin. The Tifton 85 silage can be used as a replacement for Tifton 85 hay up to 100% without changing the milk production and composition of Holstein cows.