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Björkegren, Lottie, 2013. Effects of two different light programs on milk yield, prolactin, IGF-1 and sleep in dairy cows. Second cycle, A2E. Uppsala: SLU, Dept. of Animal Nutrition and Management

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Abstract

The aim of this study was to investigate the relationship between sleep, photoperiod, milk yield and hormones connected to milk formation. Variations of prolactin (PRL) and Insulin-Like growth factor-1 (IGF-1) in plasma were measured during two different light programs. The light programs consisted of either 24 hours of light (L24:D0) or four hours of light and 20 hours of darkness (L4:D20). Five cows of the Swedish Red breed were used in a cross-over experiment and each light program consisted of five days. Milk yield was measured at every milking and milk samples were analyzed with regard to fat, lactose and protein. The difference between morning and evening milking in a 12-hour milking interval was also examined. Blood samples were collected via a permanent catheter during milking and after periods of sleep during the last 36 hours of each light program.
There were no significant differences in milk yield or milk composition between the light programs, neither did morning or evening milk yield vary. There were small variations in amounts of sleep between the two light programs. Plasma PRL did not differ significantly between the light programs besides at 1 min and 11 min after start of milking. Levels of IGF-1 were significantly higher during L4:D20. There was no significant effect of sleep on IGF-1. Sleep, light and milk formation needs to be further studied in order to investigate possible connections and underlying mechanisms.

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Syftet med studien var att undersöka hur sömn, ljus, mörker och hormoner kopplade till mjölkbildning, är relaterade. Variationer i nivåer av prolaktin (PRL) och insulin-like growth factor-1 (IGF-1) mättes i två olika ljusprogram. Ljusprogrammen bestod aningen av 24 timmars ljus (L24:D0) eller fyra timmars ljus och 20 timmars mörker (L4:D20). Fem kor av rasen Svensk rödbrokig boskap användes i en crossover-studie där varje ljusprogram bestod av fem dagar. Avkastning registrerades vid varje mjölkning och mjölkprover togs för analys av fett, laktos och protein. Skillnaden i avkastning mellan morgon- och kvällsmjölkning i ett 12-timmars mjölkningsintervall studerades även. Blodprov togs med hjälp av en permanentkateter under mjölkningen samt efter perioder av sömn under de sista 36 timmarna av varje ljusprogram.
Varken avkastning eller mjölksammansättning skiljde sig signifikant åt mellan ljusprogrammen, det fanns inte heller någon skillnad i avkastning mellan morgon- eller kvällsmjölkning. Det fanns inga stora skillnader i mängden av sömn i de två ljusprogrammen. Nivåer av PRL skiljde sig inte åt mellan ljusprogrammen med undantag för +1 min och +11 min efter starten av mjölkningen. Mängden IGF-1 var signifikant högre under L4:D20, men sömn hade ingen effekt på nivån av IGF-1. Sömn, ljus och mjölkbildning behöver undersökas mer för att förstå grundläggande underliggande mekanismer och samband.

Main title:Effects of two different light programs on milk yield, prolactin, IGF-1 and sleep in dairy cows
Authors:Björkegren, Lottie
Supervisor:Ferneborg, Sabine
Examiner:Holtenius, Kjell
Series:Examensarbete / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård
Volume/Sequential designation:401
Year of Publication:2013
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:VY001 Agricultural Science Programme - Animal Science 270 HEC
Department:(VH) > Dept. of Animal Nutrition and Management
Keywords:Dairy cows, Light program, IGF-1, Prolactin, Milk yield
URN:NBN:urn:nbn:se:slu:epsilon-s-2089
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-2089
Subjects:Animal husbandry
Animal physiology and biochemistry
Language:English
Deposited On:07 Mar 2013 13:40
Metadata Last Modified:07 Mar 2013 13:40

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