title: Milk protein responses to balanced amino acid and removal of Leucine and Arginine supplied from jugular-infused amino acid mixture in lactating dairy cows.
abstract: This study was undertaken to evaluate the milk protein response when cows were supplied a balanced AA profile and to determine whether a deficiency of Leucine (Leu) or Arginine (Arg) had a negative effect on milk protein. Eight mid-lactation Holstein cows were randomly assigned to 5-day continuous jugular infusions of saline (CTL), EAA mixture prepared on the profile of casein and supplied (in % of lysine (Lys)) 100% of Lys, 33.3% of methionine (Met), 110.2% of Leu, 43.6% of Arg, 50.8% of threonine (Thr), 81.6% of valine (Val), 69.7% of isoleucine (Ile), 61.4% of phenylalanine (Phe) and 34.2% of histidine (His) (Casein, 160 g/d), EAA mixture excluding Leu (-Leu, 163 g/d) or EAA mixture excluding Arg (-Arg, 158 g/d) in a duplicated 4 × 4 Latin square design with four infusion periods separated by 7-day interval period. The basal diet supplied 1.6 Mcal NELand 94.4 g MP per 1 kg DM to meet requirements for lactation. The Casein treatment provided a balanced supply (in % of MP) of 10.3% Leu and 5.3% Arg, whereas in the two subsequent -Leu and -Arg treatments, the concentration of Leu and Arg was reduced to 8.4 and 4.6% respectively. Dry matter intake (15.4 kg/day) was not affected by treatments. The Casein treatment increased milk yield (14.9%, p < 0.001), milk protein yield (120 g, p < 0.001) and milk protein efficiency (0.03, p = 0.099) than CTL treatment. However, the -Leu treatment decreased the responses of above-measured parameters by 6.25%, 70 g, 0.05 (p < 0.06) (compared with Casein). These effects of Leu were related to decreased Leu concentration and improved concentration of Ile and Val in plasma. The -Arg treatment decreased the plasma Arg concentration than the Casein treatment, whereby resulted in the decrease of milk yield (5.7%, p = 0.073), milk protein yield (60 g, p = 0.011) and milk protein efficiency (0.04, p = 0.037). In conclusion, supply of EAA profile of casein can increase the lactation production in dairy cows, and 8.6% of Leu in MP partly limits the milk protein response when the requirements of Lys, Met and His were met. The level of Arg at 4.6% MP is not deemed to an ideal profile, as evidenced by decreased milk protein efficiency.
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: W
authors.initials: W
authors.lastname: Tian
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: H R
authors.initials: HR
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: T Y
authors.initials: TY
authors.lastname: Wu
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: L Y
authors.initials: LY
authors.lastname: Ding
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: R
authors.initials: R
authors.lastname: Zhao
authors.affiliation: College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China.
authors.forename: E
authors.initials: E
authors.lastname: Khas
authors.affiliation: College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China.
authors.forename: C F
authors.initials: CF
authors.lastname: Wang
authors.affiliation: College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China.
authors.forename: F Q
authors.initials: FQ
authors.lastname: Zhang
authors.affiliation: College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China.
authors.forename: F Y
authors.initials: FY
authors.lastname: Mi
authors.affiliation: College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China.
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, and Key Laboratory of Grass and Herbivores of Chongqing, Southwest University, Beibei, Chongqing, China.
authors.forename: L T
authors.initials: LT
authors.lastname: Ning
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage* / Q000494:pharmacology; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001120:Arginine / Q000008:administration & dosage* / Q000494:pharmacology; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D005260:Female; D007275:Injections, Intravenous; D007774:Lactation / Q000187:drug effects*; D007930:Leucine / Q000008:administration & dosage* / Q000494:pharmacology; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D008894:Milk Proteins; D001120:Arginine; D007930:Leucine
keywords: casein profile; dairy cows; infusion; milk protein synthesis