| Five dairy farms were investigated that partiscipated the DHI test according to thegeographical distribution and the management condition of Daqing area. Some indexes andeffected factors were analysed such as the milk yield, milk fat percentage, milk proteinpercentage, SCC (somatic cell count), peak milk yield, peak day by the GLM statistical modelwith the DHI data whose irregular and missing ones were removed from2010to2013. It willoffer accurate data for planning breeding program, managing the herds, revising the diets andpreventing diseases.The results showed that:1. The average daily milk yield of individual and prospective milk yield of305d wereincreased year by year. Respectively increased from19.11kg/d in2010to23.84kg/d in2013，and from6329.78kg in2010to6,951.50kg in2013. The average daily milk yield of48.63%individuals were higher than20kg. The various indexes of No.1and No.5farm were higher thanothers significantly (p＜0.05).2. The average individual peak days of No.5farm decreased from73days in2010to51daysin2013. The milk yield of the peak days increased from26.87kg in2010to33.12kg in2013（p＜0.05）.3. The average individual milk fat percentage was3.56%, the fat in milk of18.24%individuals were lower than3.0%. The average individual milk protein percentage was3.24%.The protein in milk of25.34%individuals were lower than2.95%.4. The application of DHI kept a low individual somatic cell count and reduced the incidenceof mastitis. The average SCC was23.1×104/mL. The incidence of mastitis was35.0%, and itreduced31.9%in No.2。5. The economic loses of each cow because of SCC increasing was1730yuan in2010, and844yuan in2013, and revenue increased by51.2%.6. The parities, lactation periods and months influenced the milk fat percentage, milk proteinpercentage and SCS in varying degrees. Both milk protein percentage and milk fat percentagewere lower from Apr. to Aug., and SCC was highest in Feb., when in third parities, SCCincreased after lactation ninty day. |
PDF Full Text Request