Longevity and milk production efficiency of Latvian local breeds during last decades

The aim of the study was to analyse the longevity and the amount of energy-corrected milk (ECM) per day of local dairy cattle breeds Latvian Brown (LB) and Latvian Blue (LZ). The study was based on the data of LB genetic resources (LB) 1770 and LZ 921 cows, which were born from January 1st, 2000 till December 31st year 2015. Milk productivity and longevity of the LB and LZ cows were analysed by birth year periods: 2000–2005, 2006–2010 and 2011–2015. LZ culled cows lifespan was in average 2,762.8 ± 55.14 days, or 7.6 years and it was significantly higher than for LB. The average lifespan of LB culling cows was 6.7 years. There are cows which had closed 7–12 lactations. On average, cows’ lifespan decreased during analysed period. In general, LZ cows are characterized by higher length of productive life and milking days. LZ cows produced more EC milk during their productive life; however, they had the lower milking day ECM productivity than LB cows

Evaluation of feed conversion efficiency for different dairy cows breeds by milk yield, milk content and faecal amount

The objective of this study was to evaluation of feed conversion efficiency for Latvian Brown (LB) and Holstein Black and White (HM) dairy cows breeds to define optimal crude protein (CP) content in the feed. In the research study were completed three (A, B, C) dairy cows group (8 cows in each group) with LB and HM breed’s cows in the early lactation period, from 10 till 30 lactation days. Each groups cows were feeder with total mixed ration (TMR) with different CP content (approx. 18.0%, 17.5%, 17.0% accordingly). In the research period were controlled the amount of feed fed and regularly collected feed samples. After 21 days feeding was controlled milk yield, collected milk samples for content testing, and faecal amount and samples. Milk samples were analysed for fat, total protein (%) and urea content (mg dL-1 ). Milk samples for content parameters were analysed in an accredited milk quality laboratory. The statistical analyses were performed with the SPSS program package. The results acquired show that in all studied parameters were not significant differences between study groups. To evaluate the feed conversion efficiency during the study, we used the energy corrected milk (ECM) and the feed dry matter content during research and calculated the coefficient for each cow individually and on average in the study group. Milk yield, protein and faecal amount were significantly different among breeds. Milk urea content was average 28.5 mg dL-1 for all LB breed cows in all groups, for HM breeds it was 23.6 mg dL-1 . These results show that LB breed cows did not converse feed proteins wholesome. Total milk and faecal amount were decreased in a group with CP 17% in feed by 10% and 7% accordingly. By using this data, the farmer may make evaluations and forecast of farming efficiency; cows breed preference and environmental threats

Thermal decontamination of sewage sludge

Every year a huge amount of sewage sludge is formed at municipal wastewater treatment plants. Sewage sludge contains a sufficient amount of biogenic elements and organic components, which characterizes them as possible raw materials for the production of organic fertilizers. However, direct incorporation of these sediments into the soil is impossible due to the fact that, in addition to useful organic and mineral components, they contain pathogens, viruses and helminth eggs. The aim of the study was to optimise thermal disinfection conditions for preparing of safety sewage sludge fertilizer. Laboratory studies were carried out using sediments from wastewater treatment plants of some cities. During laboratory experiments, the conditions for thermal disinfection of sediments – the thickness of the sediment layer, the air temperature in the disinfection furnace, and the treatment time of the sediment – were determined. When conducting industrial tests of a conveyor-type sediment decontamination furnace, the operating conditions of the furnace were determined, i.e., the temperature regimes of the sludge heating zone, the decontamination zone and the cooling zone, and the optimum parameters of the sludge layer thickness on the conveyor and the conveyor speed were determined