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Räisänen, Susanna, 2016. Milk production and protein utilization in high producing dairy cows fed a low CP diet based on cereals and roughage only : a full lactation study. Second cycle, A2E. Uppsala: SLU, Dept. of Animal Nutrition and Management

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Abstract

A feeding trial investigating the effect of a concentrate diet consisting only of cereals on milk production, protein utilization and nitrogen efficiency was conducted on Swedish dairy cows. 13 SRB and 12 SH cows were randomly assigned to one of two groups: group 1 was fed a concentrate feed (Cereal), mainly consisting of barley (36%), wheat (34%), oats (25%) as well as molasses (2%) and a mineral and vitamin mix (3%), whereas group 2 had access to both Cereal and a protein rich concentrate feed (Prot) based mainly on soya bean (51%) and rapeseed cake (28%). A high quality grass silage (energy 11.4 MJ ME, CP 14.8%) was fed ad libitum, and during summer months the cows were kept on pasture, where the pasture allowance was sufficient for maintaining the production level. The cows were fed according to Swedish regulations for organic production. Milk production data as well as BCS and LW were obtained for the entire lactation, whereas blood samples and urine spot samples were collected for the first three months of lactation. Total CP content in the feed ratio was 14.0% and 16.4% for group 1 and 2, respectively. Group 1 had lower CP and energy intake, whereas the total intake and starch intake did not differ between the groups. The concentrate intake was higher in group 2 at all stages of lactation, whereas the roughage intake was higher in group 1 in mid-lactation. Total ECM production over the whole lactation did not differ between the groups, being 9760 and 9706 kg for group 1 and 2, respectively. Daily milk yield did not differ between the two groups either, being 30.5 kg/day and 31.7 kg/day for group 1 and 2, respectively. Neither did the daily ECM yield, milk fat nor protein concentrations differ between the groups. The lactose content in milk was higher in group 1 (4.78%) compared to group 2 (4.71%). When MY and ECM were grouped by early, mid and late lactation stage, group 2 achieved higher daily MY in early lactation while group 1 had higher ECM yields in late lactation. N-efficiency was higher in group 1 (36.5%) compared to group 2 (32.0%). Milk urea concentration was lower in group 1 (3.85 vs. 4.27 mmol/l), as was the daily UUN excretion (66.08 vs. 150.58 g/d). Plasma histidine concentration differed between the groups, being 34.96 and 47.7 nmol/ml in group 1 and 2, respectively. All in all, the results obtained in this study indicates that high producing dairy cows can be fed with a diet consisting only of silage and cereal concentrate without any significant reductions in production levels. Further, an increased nitrogen efficiency as well as a more persistent lactation can be seen as a beneficial effect of the used diet and the reduced CP content in the dairy cow diet.

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Ett utfodringsförsök genomfördes på svenska mjölkkor för att utforska effekten av ett kraftfoder som består enbart av spannmål på mjölkavkastning och protein utnyttjandet. 13 SRB och 12 SH kor delades i två grupper: grupp 1 utfodrades med ett kraftfoder (Cereal) som innehöll korn (36%), vete (34%), havre (25%) samt melass (2%) och en mineral och vitamin mix (3%), medan grupp 2 hade tillgång på både Cereal-fodret och ett proteinrikt kraftfoder (Prot) som huvudsakligen bestod av sojabönor (51%) och rapskaka (28%). Korna hade fritillgång på ett ensilage av högkvalitet, och under sommarmånader var de på bete där betestillgång var tillräcklig för höga betesintag. All utfodring var utformad enligt KRAVs regler för ekologisk produktion. Produktionsdata samt hullbedömningar och viktdata insamlades för hela laktationen medan blod- och urinprover samlades in för 3 första månader av laktationen. Totala råprotein innehållet i foderstaten var 14.0% respektive 16.4% för grupp 1 och 2. Råprotein och energi intaget var lägre i grupp 1, medan totala intaget samt stärkelse intaget var likadana mellan de två grupperna. Kraftfoder intaget var högre i grupp 2 i alla laktationsstadier medan grovfoder intaget var högre i grupp 1 i mitten av laktationen. Totala ECM produktion över hela laktationen skiljde sig inte mellan grupperna, 9760 kg respektive 9706 kg, för grupp 1 och 2. Inte heller mjölkavkastningen i kg mjölk, 30.5 kg/dag och 31.7 kg/dag för grupp 1 respektive 2 , fetthalten eller proteinhalten skiljde sig mellan grupperna. Laktoshalten var däremot högre i grupp 1 (4.78%) jämförd med grupp 2 (4.71%). När mjölkavkastning och ECM avkastning grupperades efter tidig, mitten, och sen laktation, hade grupp 2 högre mjölkavkastning i tidig laktation medan grupp 1 hade högre ECM avkastning i sen laktation. N-effektivitet var högre i grupp 1 (36.5%) jämförd med grupp 2 (32.0%). Koncentration mjölkurea var lägre i grupp 1 (3.85 vs. 4.27 mmol/l), liksom den dagliga utsöndring av UUN (66.08 vs. 150.58 g/d). Halten histidin i plasma skilde sig mellan grupperna, och var 34.96 respektive 47.7 nmol/ml för grupp 1 och 2. Resultaten från denna studie tyder på att högproducerande mjölkkor kan utfodras med bara spannmål och vall foder utan minskningar i produktionsnivåer. Det ger dessutom ökad N-effektivitet och mer uthållig mjölkavkastning mot slutet av laktationen.

Main title:Milk production and protein utilization in high producing dairy cows fed a low CP diet based on cereals and roughage only
Subtitle:a full lactation study
Authors:Räisänen, Susanna
Supervisor:Spörndly, Rolf
Examiner:Bertilsson, Jan
Series:Examensarbete / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård
Volume/Sequential designation:573
Year of Publication:2016
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:VM003 Animal Science - Master's Programme 120 HEC
Department:(VH) > Dept. of Animal Nutrition and Management
Keywords:dairy cows, lactation, milk production, protein utilization, nitrogen efficiency, dietary protein level
URN:NBN:urn:nbn:se:slu:epsilon-s-5581
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-5581
Subjects:Animal husbandry
Animal feeding
Language:English
Deposited On:02 Aug 2016 10:39
Metadata Last Modified:02 Aug 2016 10:39

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