PROCJENA UNOSA ENERGIJE I USPOSTAVA SPOLNOG CIKLUSA KOD VISOKOMLIJEČNIH KRAVA. (Croatian)

THE ESTIMATE OF ENERGY INTAKE AND reproductive activity iN HIGH PRODUCING DAIRY COWS. (English)

Establishing the ovarian cycle in high-yielding dairy cows after calving is a common problem on farms with intensive milk production. High milk production requires an increased intake of energy and other nutrients necessary for milk synthesis, and in case of their deficiency, metabolic and reproductive disorders occur during lactation. In this paper we analyzed the energy intake and the reproductive indicators of high yielding dairy cows. Based on the protein and urea content and the ratio of milk fat and protein content, it was determined that 17.5% of the milk samples came from cows with insufficient energy intake. The period of early lactation (the first 60 days) is the most sensitive period in cows regarding to the sufficient energy and proteins intake. Results showed that 45% of the milk samples analyzed in this period have a deficit in energy intake, and in 16.5% of the samples, IMB was higher than 1.5, which suggests extensive mobilization of fat from body storages and the appearance of metabolic disorders. The establishment of the ovarian cycle expressed as the period until the first mating, in most cows was within 90 days after calving (74%), while in only 9% of cows this period was longer than 120 days. Despite this, in more than 32% of cows, pregnancy occurred after the 120th day of lactation, which indicates the absence of ovulation and/or the existence of unfavorable conditions for embryo survival (early embryonic mortality). [ABSTRACT FROM AUTHOR]

Uspostavljanje spolnog ciklusa kod visokomliječnih krava nakon teljenja česti je problem na farmama koje imaju intenzivnu proizvodnju mlijeka. Visoka proizvodnja mlijeka zahtijeva povećani unos energije i drugih hranjiva potrebnih za sintezu mlijeka i u slučaju njihova nedostatka dolazi do metaboličkih i reproduktivnih poremećaja tijekom laktacije. U radu je analizirana razina opskrbljenosti krava sa energijom te reproduktivni pokazatelji kod visokomliječnih krava. Na temelju sadržaja proteina i uree te odnosa sadržaja mliječne masti i proteina u mlijeku utvrđeno je da 17,5 % uzoraka mlijeka potječe od krava nedovoljno opskrbljenih energijom. Razdoblje rane laktacije (prvih 60 dana) je najosjetljivije razdoblje s obzirom na dostatnu opskrbu energijom i proteinima kod krava na što ukazuje činjenica da 45 % uzoraka mlijeka analiziranih u ovom razdoblju ukazuje na deficit unosa energije, a u 16,5 % uzoraka utvrđen je omjer masti i proteina u mlijeku (IMB) >1,5 što sugerira opsežnu mobilizaciju masti iz tjelesnih rezervi i pojavu metaboličkih poremećaja. Uspostava spolnog ciklusa izražena kao razdoblje do prvog pripusta u većine krava bila je unutar 90 dana nakon teljenja (74 %) dok u svega 9 % krava to razdoblje je bilo dulje od 120 dana. Unatoč tome u čak 32 % krava graviditet je nastupio iza 120. dana laktacije što ukazuje na izostanak ovulacije i/ili postojanja nepovoljnih uvjeta za preživljavanje embrija (rana embrionalna smrtnost). Povezanost između pojedinih sastojaka mlijeka i reproduktivnih pokazatelja nije utvrđena. [ABSTRACT FROM AUTHOR]

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