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Poster De Conférence Année : 2016

Impacts of energy level of the diet and nature of forage on milk spontaneous lipolysis in dairy cows

Résumé

Spontaneous lipolysis (SL) is one of the criteria of milk technological and organoleptic quality. Few studies have been done to investigate the impact of feeds on SL although milk quality is hardly related to feeding systems. This trial was aimed to evaluate the effects of the energy level of the diet and the nature of forage on SL. Thirty two cows were divided into 4 groups according their diet. Diets were based on maize silage or haylage and dried grass. Two levels of feed restriction were applied: ‘non-restricted’ which cows were fed at 100% of ad libitum dry matter intake (DMI) and ‘restricted’ which cows were fed at 75% of ad libitum DMI. The trial was conducted in a reverse design on the energy level of the diet. Cows were followed during 11 weeks: 3 control weeks and 6 experimental weeks divided in 2 periods. Milk samples were collected from morning and evening milkings at the end of each period for fat, protein, fat globule size and SL determination. Data were analyzed with SAS GLM procedure. Milk fat was lower when cows were fed with maize silage (3.53 vs 3.91%) and was not affected by feed restriction. Milk fat globule size was lower when cows were fed with maize silage (average diameter: 3.25 vs 3.55 μm) and was not affected by feed restriction. SL was sharply higher in milk from evening milkings compared to morning milkings (0.72 vs 0.29 mEq/ 100 g of fat). In morning milks, SL was higher when cows were fed with maize silage (0.40 vs 0.20 mEq/100 g of fat) and restricted (0.35 vs 0.26 mEq/100 g of fat). In evening milks, SL was higher when cows were restricted (0.88 vs 0.60 mEq/100 g of fat) and there was no significant effect of the nature of forage. We supposed that the mechanisms of SL are different in morning and evening milks. Higher impact of feed restriction on evening milks would be explained by higher energy requirements during the day. Further investigation will be done to clarify the mechanisms behind.
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Dates et versions

hal-01455940 , version 1 (03-02-2017)

Identifiants

  • HAL Id : hal-01455940 , version 1
  • PRODINRA : 378578

Citer

Élise Vanbergue, Jean-Louis Peyraud, Catherine Hurtaud. Impacts of energy level of the diet and nature of forage on milk spontaneous lipolysis in dairy cows. 67. Annual Meeting of the European Federation of Animal Science (EAAP), Aug 2016, Belfast, United Kingdom. Wageningen Academic Publishers, Annual Meeting of the European Association for Animal Production, 22, 2016, Annual Meeting of the European Association for Animal Production. ⟨hal-01455940⟩
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