Search

In order to determine the persistence of heat stress effect in dairy cows regarding the breed, parity and susceptibility to heat stress, over 1.9 million of test-day records from Holstein and Simmental cows reared in Croatia were used. The persistence of heat stress effect in the subsequent milk recordings was determined in cows that had significant decrease of daily milk yield at different THI threshold value (65, 70, 75, 80, and 85). The obtained results indicate that cows heat stressed at lower THI threshold value had higher proportional drop of daily milk yield in subsequent milk recordings. Also, primiparous and Simmentals experienced higher proportional drop when compared to multiparous and Holsteins. The negative effect of heat stress on daily milk contents that existed in all cows was more pronounced in the 2nd subsequent milk recording. The determined increase of somatic cell count in more heat stress sensitive Holsteins (THI in 65, 70, 75) indicates that Holstein cows, in terms of heat stress, also become more susceptible to mastitis. Finally, the lower was the THI threshold value, the stronger and more persistent was the heat stress effect. Considering the quite probable increase of the frequency of heat stress days, it is necessary to develop an adequate strategy for dairy farming. Aiming the accurate answer to the problem of heat stress in this region, it is necessary to conduct further research on genetic evaluation. [ABSTRACT FROM AUTHOR]

In order to analyse metabolic disorders in Simmental cows, 2.641.223 test-day records have been used. The metabolic disorders prevalence risk was indicated by the fat to protein (F/P) ratio, while the subclinical disorder was demonstrated using the F/P ratio and daily production. In terms of the ketosis prevalence risk (KPR), the highest prevalence risks occurred at the 20th lactation day in all tested cows with exception of cows in parity P4+ which experienced peak prevalence risk at 25th lactation day. A steady decrease of KPR after peak prevalence was observed in all animals except the 3rd lactation cows which experienced the second peak prevalence at the 30th lactation day, after which the prevalence risk continued to decline. The highest acidosis prevalence risk (APR) was detected among 4+ parity cows. Considering the lactation stage, the highest APR occurred within the first 10 days, with the indication from 16 to 23 %, depending on parity. The peak prevalence risk was followed by a considerable decline during the ensuing 20 days. The prevalence risk began to increase among all cows after the 25th lactation day. Furthermore, there was a considerable decrease in a daily milk yield and variation of daily milk contents due to subclinical disorders. The most noticeable drop in daily milk yield, for both ketosis/acidosis, was detected in cows in 4+ parity in the amounts of 7.45 kg/day and 2.73 kg/day respectively. There was also a production decline in the subsequent milk controls. Subclinical disorders can also substantially change daily milk contents. The daily fat content was considerably reduced by the subclinical ketosis and the same parameter was considerably increased by the subclinical acidosis. The opposite trends were detected for daily protein content. Since indication criteria was set on Holstein population and considering the fact that Simmental cows produce noticeably less, some adjustment is needed before a routine use of test-day records for early detection of metabolic disorders in dairy Simmental herds. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the differences in milkability, milk and health traits in Holstein and Simmental dairy cattle due to parity. Following traits were analysed: milkability (duration of milking, MT; milk yield per milking, MYM; maximal, MMF and average milk flow, AMF), milk traits (daily milk yield, DMY; daily fat content, DFC; daily protein content, DPC; daily lactose content, DLC; urea, UREA) and health traits (logarithmic somatic cell count, SCClog and teatend hyperkeratosis, TEH). Significant (p<0.05; p<0.01; p<0.0001) differences between parity in MYM, DMY, MMF, DPC and DLC was determined. Also, significant (p<0.0001) difference in the teat-end hyperkeratosis score were found between cows in 1st and 2nd as well as between cows in 1st and ≥3rd parity. The cows in 1st and 2nd parity had similar SCClog, while significant (p<0.05) difference was found between SCClog in cows in 1st and cows in ≥3rd parity. The obtained results indicate that the parity significantly affect the milkability, milk and health traits. Since the hyperkeratosis level is highly correlated to the mastitis incidence risk, the regular teat-end scoring should be used in order to ensure quality machine milking and to minimize mastitis incidence risk. [ABSTRACT FROM AUTHOR]

Considering the rapid climate changes worldwide, with the purpose to reduce financial losses for dairy farmers and enable a more sustainable farming as well, there is an increasing necessity to implement breeding values for heat resistance in breeding strategies. The estimation of breeding values requires a determination of temperature-humidity index (THI) threshold value. Therefore, the objective of this study was to determine the temperature-humidity index (THI) threshold values for daily milk yield, daily fat and protein content of milk produced by Holsteins and dairy Simmentals in Croatian farms. With that purpose, 1.070,554 test-day records from 70.135 Holsteins reared on 5.679 farms and 1.300,683 test-day records from 86.013 Simmentals reared on 8.827 farms in Croatia were compared to records of ambient temperature and relative humidity collected in the barn, during regular milking recordings from January 2005 to December 2012. Accordingly the following conclusions could be drawn: threshold values for daily milk yield were highly dependant on the parity and breed (Holsteins: 68, 69 and 72 for 1st, 2nd, 3+ parity; Simmentals: 77 for 1st); daily fat and protein contents showed a highly significant decrease due to heat stress condition (THI in 66-80) in both, Holstein and Simmental cows, and in all parity classes; multiparous cows were more resistant to heat stress than primiparous; Simmental cows were more resistant to heat stress than Holsteins. [ABSTRACT FROM AUTHOR]

Anatomical characteristics of dairy cattle are not equal for all breeds, meaning that the morphological traits of udder and teats could favor an individual performance or a determined breed. Changes in teat tissue after machine milking occur because of the negative influence of the vacuum and mechanical forces of the teat cup liner. Duration and performance of machine milking also depend on the udder and teat conformation and milkability traits of cows. The aim of this study was to determine the differences in morphological characteristics of Simmental and Holstein cows before and after machine milking, as well as to elaborate the differences in some of milkability traits of the cows during process of milking. A correlation (from -0.30 to 0.37) was determined between exterior and interior traits of teats and the performance of milkability traits. In both cow breeds, statistically significant difference (p<0.0001) was found between the pre- and post-milking values in all investigated traits, with exception of teat end width. Holstein cows had significantly (p<0.001) higher amount of milk per milking, maximum and average milk flow, while cows of the Simmental breed had longer milking time duration, but without statistical significance. In comparison to Holstein breed, results of internal morphological traits of teats showed that cows of Simmental breed had longer teat canals and wider teat ends for both front and rear teats. Holstein breed compared to Simmental had thinner teats wall, but wider teat cistern. If compared to pre-milking stage, differences in teat cistern width and teat wall thickness that occur after milking were more expressed in the Holstein breed than in Simmental. Simmental cows had significantly (p<0.05) longer and wider rear teats. Future research should focus on proving the differences in changes of teat tissue due to milking between different groups of cows, as depending on the milk flow. Ultrasound method of recording can be applied in such assessment. [ABSTRACT FROM AUTHOR]

Milkability traits have an increasing importance in modern cattle production, although they are the secondary selective trait. The machine milking of cows has indicated that there is no complete alignment between the machine and the animals, what lead to increasing duration of milking and disturbances in health of udder. Because of that, the aim of this study was to investigate the influence of the ordinal number of lactation and stage of lactation on milkability traits (amount of milk per milking (KMM), maximum milk flow rate (MPM), average milk flow rate (PPM), duration of the start of milk flow (tS500), duration of the ascending phase of milking (tUFM), duration of the plateau phase of milking (tPFM), duration of the descending phase of milking (tSFM), duration of the main phase of milking (tGFM)), and recommend the same for the selection work. The study was done on 322 Holstein cows in the period from the first to third lactation, arranged in three stages of lactation (the first of the 50-90 day, the second stage of the 91-135 day and a third of 136-180 day of lactation). The results showed that the ordinal number of lactation had a highly statistically significant influence (P<0.01) on KMM and MPM, and on the PPM and tGFM (P<0.05). Statistically significant influence of the stage of lactation on the KMM was recorded in the first and second lactation (P<0.05) respectively in the third lactation (P<0.01). Was recorded a significant positive influence of KMM (P<0.05) on the MPM, tPFM, tSFM and tGFM (r = from 0.22 to 0.52). The negative correlation of the MPM (P<0.05) was recorded with some parts of the milking phase duration (r = -0.14 to -0.47). The results indicate that there are opportunities for selection work to improve milkability traits, which can have 10 a positive impact on the economy of expenditure of time during milking, and indirectly improve the health of the udder. [ABSTRACT FROM AUTHOR]

The final result of milk quality management is a superior product with high quality levels of all intrinsic and extrinsic components. To achieve this, most activities in the management process should be directed towards the quality components that are recognized by the average consumer of milk. To determine these factors, an indicative research was carried out on a sample of 1,157 respondents among the young population. Regarding the intrinsic components, the results indicate that young consumers mostly appreciate the taste and milk fat content in the range 2.8-3.2 %, whereas regarding the extrinsic components they value price and the origin of products, that is, the origin of milk. The last component has not been fully used in promotional efforts of producers in their advertising of milk, especially in a sub segment of urban young consumers. A stronger emphasis of this would help producers to differentiate themselves, and achieve competitive advantage on domestic and international markets. [ABSTRACT FROM AUTHOR]