Effects of zinc amino acid complex on mammary epithelium and dairy food chemistry

• Published in: Journal of animal science 2016-10, Vol.94, p.753-753
• Main Authors: Shaffer, J E, Pandalaneni, K, Mamedova, L, Defrain, J, Amamcharla, J K, Bradford, B J
• Format: Article
• Language: English
• Subjects: Acclimation; Acclimatization; Amino acids; Animal sciences; Apoptosis; Cattle; Clusterin; Composition effects; Dairy cattle; Dairy products; Epithelium; Feed additives; Food; Grain; Integrity; Lactalbumin; Lactation; Lactose; Mammary gland; Methionine; Milk; Milk production; Minerals; Nutrient deficiency; Secretion; Selenium; Trace minerals; Transcription; Vitamin deficiency; Zinc
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jam2016-1550

Objectives of this study were to determine effects of supplemental zinc level and source on mammary epithelial barrier integrity and milk chemistry in dairy cattle. In a mouse model, moderate zinc deficiency was shown to dramatically impact milk secretion and mammary gland involution. In addition, through multiple pathways, zinc is known to impact apoptosis in mammary and other epithelial tissues. To test for similar effects in cattle, 12 multiparous Holstein cows in mid to late lactation (132 ± 21 DIM) were blocked by milk production and randomly assigned to treatment sequence in a replicated 3 x 3 Latin square experiment. Each treatment period lasted 21 d (17 d of acclimation and 4 d of sampling). Treatments consisted of 1) 0.97 g zinc/d provided as ZnSO4 (approximately 30 mg zinc/kg diet DM; 30-ZS), 2) 1.64 g zinc/d as ZnSO4 (60-ZS), and 3) 0.55 g zinc/d provided as ZnSO4 plus 1.13 g zinc/d provided as a zinc methionine complex (60-ZM; Zinpro Corp., Eden Prairie, MN). Treatments were also balanced for metabolizable methionine using Smartamine M (Adisseo Inc., France). Cows were housed in individual tie stalls, given ad libitum access to water, and fed a balanced basal ration twice daily. Treatments were provided daily in an oral bolus and contained all supplemental trace minerals except for selenium, which was included in the grain mix. Measurements were analyzed with a mixed model using fixed effects of treatment, period, and their interaction and the random effect of cow. Significance was declared at P < 0.05 and tendencies at P < 0.10. Feed intake tended to increase for 60-ZS cows (P = 0.06) and 60-ZM cows tended to have increased milk fat percentage (P = 0.08) compared with 30-ZS cows. No other effects on milk composition, yield, or production efficiency were observed. No effects of treatments were observed on heat coagulation time or the percent of NPN in the milk. Plasma electrolyte, lactose, and a-lactalbumin levels as well as transcript abundance of genes implicated in zinc transport (ZnT2), tight junction formation (occludin), and apoptosis (clusterin) were also unaffected by treatment. In conclusion, zinc supplementation of dairy rations at 60 ppm as opposed to 30 ppm did not appear to impact the integrity of the blood milk barrier or dairy food properties of milk.