Vpliv ultravijoličnega-B sevanja med robotsko molžo na koncentracijo vitamina D v krvi krav molznic črno-bele pasme

Hodnik, Jaka Jakob (author), Starič, Jože (mentor)

Z našo raziskavo smo želeli opredeliti varen odmerek UV sevanja za sintezo vitamina D pri kravah molznicah črno-bele pasme in preveriti uporabnost obsevanja z UVB lučjo ozkega spektra, omejenega na čas robotske molže za sintezo vitamina D. Ugotoviti smo skušali tudi vpliv dolžine dlake in barve kože oziroma dlake na sintezo vitamina D pri govedu. V prvi del raziskave smo vključili 21 krav in telic črno-bele pasme z dveh kmetij, ki smo jih z naraščajočimi odmerki z UVB lučjo obsevali na 8 odlakanih in na 8 obritih mestih. V drugi del raziskave smo vključili 51 krav črno-bele pasme, ki smo jih na podlagi mlečnosti v predhodni laktaciji, dneva po telitvi in deleža črne dlake na hrbtu enakomerno in naključno razdelili v tri skupine. Krave v prvi skupini smo obrili vsaka dva tedna in jih obsevali z odmerkom 80 J/m2, krave v drugi skupini z maksimalnim odmerkom, ki ga je dopuščala dnevna robotska molža, a ni presegala 360 J/m2, tretja skupina krav pa je bila kontrolna skupina. V času raziskave smo kravam štirikrat odvzeli kri, in sicer prvi dan ter 7 dni, 30 dni in 60 dni po začetku obsevanja, ter z uporabo avtomatske imunsko-encimske fluorescenčne metode določili koncentracijo 25-hidroksivitamina D. V prvem delu postopka smo ugotovili, da se rdečina na beli koži pojavi pri odmerku UVB 329 J/m2, na odlakani koži pa pri odmerku UVB 5595 J/m2, ter da je slednji odmerek linearno odvisen od dolžine dlake in da je za povzročitev rdečine na odlakani koži potreben značilno višji odmerek. V drugem delu raziskave smo ugotovili, da je v času robotske molže mogoča sinteza vitamina D pod vplivom UVB luči ozkega valovnega spektra. V povprečju so največ vitamina D proizvedle obrite krave (13,37 ng/mL), sledile so odlakane krave (9,96 ng/mL), medtem ko so najmanj vitamina D proizvedle krave iz kontrolne skupine (5,11 ng/mL). Ugotovili smo, da je sinteza vitamina D v koži odvisna tudi od barve kože, medtem ko vpliva barve dlake na sintezo vitamina D nismo potrdili. Naša raziskava je prva raziskava o konkretni opredelitvi minimalnega odmerka UVB za povzročitev rdečine pri kravah molznicah črno-bele pasme na standardiziran način in omogoča primerjavo odmerkov med različnimi raziskavami. Ker ugotovljeni odmerek v zmernih geografskih širinah zlahka presežemo, je pomembno, da imajo krave na paši zavetje, kamor se lahko umaknejo z neposrednega sončnega sevanja. Ugotovili smo tudi vpliv dlake in barve kože na kožno sintezo vitamina D pri kravah črno-bele pasme in ponudili nov način nadomeščanja vitamina D, ki ne moti dnevne rutine komercialnih farm.

• Language: Slovenian
• Keywords: ultravijolični žarki, vitamin D, eritem, radioterapija, kri, kemične analize, laktacija, govedo
• Work type: Doctoral dissertation
• Organization: VF - Veterinary Faculty
• Year: 2023
• PID: 20.500.12556/RUL-144432
• Publication date in RUL: 22.02.2023

Secondary language

• Language: English
• Title: The influence of ultraviolet-B irradiation limited to robot milking time on blood vitamin D concentration in Holstein-Frisian dairy cows

Abstract

The goal of our study was to determine a safe UV irradiation dose for vitamin D supplementation in dairy cows of the Holstein Friesian breed and to investigate the utility of narrow-band UVB irradiation limited to robot milking time for vitamin D supplementation. We also wanted to determine the influence of hair and skin and/or hair colour on cutaneous vitamin D synthesis in cattle. For the first part of our study, we enrolled 21 cows and heifers of the Holstein Friesen breed from two farms. We irradiated them with a raising dose of irradiation using a narrow-band UVB light on 8 hair-covered and 8 shaven areas. In the second part of the study, we enrolled 51 cows of the Holstein Friesen breed, which we split into three equal and random groups based on milk yield in the previous lactation, days after calving and the percent of black hair on the back. The first group was shaven every two weeks and irradiated with a dose of 80 J/m2, the second group was irradiated with a maximum dose daily robot milking time would allow but did not exceed 360 J/m2, the third group served as a control group. During the study the cows were blood sampled four times on the first and at 7 days, 30 days and 60 days after the start of irradiation and the concentration of 25-hydroxyvitamin D was determined using an automated immune enzyme fluorescence method. In the first part of the study, we found that erythema on shaven will appear at a dose of 329 J/m2 and on haired skin at a dose of 5595 J/m2 and that the latter dose was linearly dependent on hair length, therefore, a significantly higher dose is needed to produce erythema on haired skin. In the second part of our study, we found that vitamin D supplementation using a narrow-band UVB light limited to robot milking time is possible. On average the shaven cows produced the most vitamin D (13,37 ng/mL), followed by the haired group (9,96 ng/mL), while the control group produced the least vitamin D (5,11 ng/mL). We also found that cutaneous vitamin D synthesis is dependent on skin colour; however, we could not confirm an effect of hair colour. This study is the first to determine the minimal erythema dose in Holstein Friesen dairy cattle in a standardised way, which allows the comparison of doses between different studies. The determined doses are easily exceeded at mild latitudes; therefore, it is important that cattle on pasture have shelter where they can get out of direct sun irradiation. We also found an effect of hair and skin colour on cutaneous vitamin D production in Holstein Friesen cattle and put forward a new way of vitamin D supplementation that does not interfere with daily farm routine.

• Keywords: ultraviolet rays, vitamin D, erythema, radiotherapy, blood chemical analysis, lactation, cattle