The aim of the work is to investigate raw milk from different bulls' daughters to clear up the influence of cows' genetic predisposition to milk microbial contamination and somatic cell count (SCC). Particular attention is paid to develop productive cow milk yield, milk fat, milk protein and in recent years, the SCC heredity. The literature describes a variety of lines and families, representatives of the resistance to certain diseases (leucosis, mastitis, tuberculosis, brucellosis, foot disease), it shows the determination of a genetic factor for this trait. If the selection results show increased resistance to a disease, then this indicates a genetic disease resistance and shy. The paper focuses on microbial contamination of raw milk at 7 different studies of bull daughters in the same line for housing, feeding and conditions of use. Raw milk samples were obtained from the breed Latvian brown (LB) from dairy cows shed of cattle shed Saujas, which belongs to SIA Palsa and is located in the civil parish Varini, Smiltene county in the year 2008/2009. Compared between the lines of bulls' daughter milk yield of the sample average value of the uniformity of variance analysis shows that they significantly differ (F=2.452, p=0.039). Comparing each line of bulls' daughters SCC of the sample average value of the uniformity of variance analysis showed that the SCC was statistically significantly different (F=2.083, p=0.075) of the various lines of bulls daughters.

The European Union livestock sector is a major player of the agricultural economy and its land use, and livestock is one of the fastest-growing sectors in agriculture, potentially presenting opportunities for economic growth and poverty reduction in rural areas. In Latvia, the year 2014 was quite difficult for the dairy industry both due to Russia’s embargo on dairy product import and low milk purchase prices and due to concerns that milk quotas had been exceeded. It is therefore important that cows are healthy and no additional losses are suffered from mastitis. Mastitis is a complex disease involving many factors, which is mainly caused by bacteria and there is no simple model that encompasses different possible aspects. Therefore, the research aim is to assess the effects of mastitis in cow herds for farms in Latvia. The research study proceeds in two stages or phases: firstly, to review the scientific literature on mastitis problems and solutions to the problems in other countries, secondly, to survey dairy farms of various sizes in the regions of Latvia in order to examine the real situation concerning mastitis and its effects on the economy of farms. A survey results of 74 farms in Latvia revealed that 90.5% of the farms had problems with mastitis. Consequently, if sick cattle are timely culled, it is possible to keep the herd milk yield without a significant drop. In case of cows with mastitis, farms suffer losses from smaller quantities of milk produced depending on farming intensity and due to cows culled with mastitis.

Advances in milk production and the expansion of dairy herds have increased the need for improved manure management and whole farm nutrient balance. It is well known in dairy management that the balanced feeding and holding technology is an important level by which milk production and milk composition can be modified. The objective of this study was to evaluate urea content and urea yield in different farms with different holding technologies. Four farms represent three cow breeds (Holstein Black and White, Latvian Brown, and cross breed XP). Individual cow milk samples (n=2740) were collected monthly from September 2009 to November 2010. Milk samples were analyzed for total protein, casein, fat, lactose, and urea content with instrumental infrared spectroscopy method. The average milk yield per cows in farms was significantly different (from 27.9 to 17.0 kg per control day). The urea content in cow milk was between 20.3 to 46.6 mg dLE-1. The average urea content in farms A, B and D was up to standard (from 15.0 to 30.0 mg dLE-1). In the farm C, average urea content ranged between 17.4 and 79.9 mg dLE-1, which indicated problems in feeding or management in the farm. It was established that milk urea content and yield significantly (p is less than 0.05) varied in farms with different dairy cow holding and feeding technologies. Urea content can be used to evaluate feed protein utilization in farms and predict environmental pollution.

The aim of the research was to evaluate the variability of milk yield and composition for goats with different kid suckling periods. The research was carried out in 2011 and 2012 on a farm where goats of Latvian breed were reared. In both years goats kidded in February and March. Each group included 10 animals. In the first group the kids were weaned on the first day of kidding (A1), in the second – on the 30th day (A30) but in the third – on the 60th day (A60) after kidding. The amount of the milk yield was measured in five successive days after the kid weaning. Milk samples were analysed in an accredited milk laboratory. The highest milk yield was obtained from the goats when kids were weaned immediately after the birth, and samples were taken starting with the 6th day of lactation (2.10 + 0.05 kg), but the lowest from the goats with suckling period of 60 days – 1.68 ± 0.03 kg. The average milk fat and protein content of the goats from the group A1 (53.6 ± 0.92 and 41.6 ± 0.66 g kgE-1), was significantly higher than from the groups A30 and A60 (p is less than 0.05). The average variability of milk yield proved to be from 4.9% in the group A1 to 10.5% in the group A30. The lowest fat content variability was observed for goats of the group A1 in both years – 8.9% and 10.7%, but the highest 20.5% in the group A60 in the first year. The highest variability of milk protein content was observed in the group A30 – 14.8%.

The objective of the study was to examine how the circumstances of different bull daughters – Latvian Brown cow - group productivity levels correlate with the blood biochemical composition indices in Latvian conditions. The daughters of seven bulls, selected for our research trial, were kept in the same barn and under rearing conditions. Their blood samples were taken in a single sampling activity and analyzed for blood serum biochemical averages. Also Cu, Fe, Zn, Mn and Mg were detected in blood serum and the values found were compared with values fixed in regulatory documents. There were changes in Cu levels (daughter groups of four bulls), in Zn levels (one group); Mn level was lower in all groups and Mg level was higher in 6 groups. The altered biochemical parameters of blood were assessed from the pathogenetical point of view and compared with productivity averages in the progeny groups. The correlation factors suggested that there exist a strong positive correlation (p is less than 0.05) among a number of indicators, such as aspartate aminotransferase (ASAT) and protein r = 0.823; ASAT and somatic cell count (SCC), r = 0.737; blood protein and milk protein r = 0.903 - 0.917; albumins and protein r = 0.964; blood urea and milk protein r = 0.931 - 0.984 along with additional correlations. The correlation factors for the progeny group of each bull differed. The data obtained shows that the Latvian Brown cows crossed with other breeds produce cows with new genetic traits.

The aim of the present research was to evaluate the affect of genetic and environmental factors on the variability of the goat milk yield, fat and protein content in goat milk in Latvia. Data of 6067 lactation records from 2400 goats of six different breeds were analysed in the period of 2001 to 2010. The highest milk yield (662.7±14.58 kg) was obtained in 2002, the highest fat content (40.7±0.05 g kgE-1) – in 2004, but highest protein content (32.7±0.19 g kgE-1) – in 2008 (p is less than 0.05). Basically there are two goat breeds in Latvia: Latvian goats and Saanen goats. In the research, 3261 Latvian and 2032 Saanen goats in closed lactations were analysed. It was found that Saanen goats gave the highest milk yield (579.3±5.01 kg), but Alpine goats – the highest fat and protein content (respectively 41.7±0.63 and 32.3±0.30 g kgE-1; p is less than 0.05). It was observed that most of all the goats kidded in winter (2379) and spring (3378). The highest milk yield (583.8±7.39 kg) was determined for goats kidded in winter season, but the highest fat content (41.8±0.06) and protein content (32.3±0.03) – for goats kidded in summer season. The average milk yield in the first lactation (1636) was significantly lower than in the third lactation (578.0±8.34; p is less than 0.05) when the goats produced the highest milk yield in the research.

The treatment of ketosis with glycerol was first introduced in the 1950s. Currently, the availability of glycerol as a feed supplement for dairy cattle has increased due to the rapid expansion of the biodiesel industry. It has been suggested that glycerol can be used as a dietary glucose precursor for dairy cows in a similar way to propylene glycol. This study examined the effect of orally administrated crude glycerol on milk production and composition, and energy-status related blood metabolites of primiparous (n=4) and multiparous (n=4) Holstein dairy cows in the first three weeks of lactation. The treatment group cows were given an oral drench of 500 mL of crude glycerol once a day before the morning feeding. Long-term oral drenching of crude glycerol had no effect on dry matter intake (DMI), but there was a positive effect on milk yield. Most milk composition values were not affected by the treatment, but treatment groups had lower milk protein levels. Blood glucose and insulin concentrations were declined with glycerol administration.

Milk production and milk composition are of prime economic importance for farmers. It is well known in dairy management that the balanced feeding and holding technology is an important lever by which milk production and milk composition can be modified. The objectives of this work are to establish relation among milk protein and urea content in different farms. Four farms represent three cow breeds (Holstein Black and White, Latvian Brown, and cross breed XP). Individual cow milk samples (n=8400) were collected monthly from September 2009 to November 2010. Milk samples were analyzed for total protein, casein, fat, lactose, and urea content with instrumental infrared spectroscopy method. The average milk yield in farms was significantly different (from 26.8 to 16.0 kg per control day), and average protein content varied from 3.32 g kgE-1 to 3.62 g kgE-1. The urea content in cow milk was between 21.3 to 42.6 mg 100 mLE-1. The average protein content was higher and significantly (p is less than 0.05) different in first yield level (up to 15 kg) for all farms. Overall, in different farm and milk yield levels correlation between protein and urea was low or very low. In the farm C, average urea content ranged between 30.0 and 60.0 mg 100 mLE-1, which indicated problems in feeding or management in the farm. It was established that milk productivity traits significantly (p is less than 0.05) varied in farms with different dairy cow holding and feeding technologies and milk protein and urea content significantly (p is less than 0.05) varied for cows with different milk yield per day.

Live weight and body condition are indicators for dairy cow’s (Bos taurus) health, milk productivity and reproduction. Live weight and body condition are defined by genetic and non-genetic factors. These factors are dependent on dairy cows growing and welfare. The aim of research was to analyze body condition relationship with milk productivity and live weight. Data were collected from 49 different breed and lactation dairy cows. Research location was Latvia University of Agriculture Research and Study farm ‘Vecauce’. Data were collected from October 2013 to January 2014. Body condition score of all cows decreased from 2.8 ± 0.05 to 2.5 ± 0.04 points in research period. Milk yield increased from 35.6 ± 0.79 kg in the 1st recording to 40.9 ± 1.12 kg in the 2nd recording. Milk yield decreased in the 3rd recording (p is less than 0.05). Fat content was the lowest in the 2nd recording (35.5 ± 0.09 g kgE-1). Protein content was significantly different in the 1st and 2nd recordings (p is less than 0.05). Somatic cell changes were not significant. Body condition decreased of older lactation cows, but milk yield increased at the same time. Milk yield was significantly the greatest in red breed group, compared with Holstein black and white cows (51.1 ± 3.21 kg vs. 41.4 ± 0.78 kg; p is less than 0.05). Body condition score significantly affected live weight in such body condition score groups: less than 2.5 points, 2.75 to 3.0 points. Effect was not significant on live weight in body condition score 3.25 less than group. Milk productivity and quality traits were not affected by the body condition score (p is less than 0.05).

The aim of our study was to determine up to what extent the number of services per calving (NSPC) affects dairy cow productive and reproductive performance. The study contains data from the Agricultural Data Centre of Latvia about 26888 Latvian Brown (LB) and Holstein Black and White (HBW) breed cows that were born from year 2005 – 2010, closed at least 5 full lactations and were culled from herds. In data set we have included data about cow milk productivity (calculated in ECM), longevity traits and reproduction traits. The reproduction traits included the number of services per conception (NSPC), calving interval (CI) and calving to conception interval (CCI) in the first five lactations. The average lifespan of LB and HBW dairy cows was 3149.5 days and in this period 39570.6 kg ECM were obtained. LB breed cows were characterized by 23.5 days longer lifespan and by 6035.4 kg ECM lower lifetime milk productivity than HBW breed cows, but they showed higher reproduction trait scores than LB breed group. HBW cows had a significantly (p is less than 0.05) higher NSPC, CCI, number of milking days (MD) and CI than LB breed cows in all five analysed lactations. The NSPC in the first lactation increased the calving age at the fifth lactation – cows with NSPC in the first lactation is greater than 4, fifth time calved 170.7 days in LB breed group and 190.8 days in HBW breed group later than cows with one NSPC in the first lactation.