title: Composition of colostrum from dairy heifers exposed to high air temperatures during late pregnancy and the early postpartum period.
abstract: This study examined the effects of heat stress on composition of colostrum from primiparous cows during late pregnancy and the early postpartum period. Two groups of 6 Holstein heifers were utilized. During the last 3 wk of pregnancy and during the first 36 h after calving, one group was exposed to thermal comfort (temperature-humidity index = 65); the other group was exposed to high air temperatures (temperature-humidity index = 82 from 0900 to 2000 h and temperature-humidity index = 76 from 2100 to 0800 h). Heifers under heat stress had higher rectal temperatures and respiratory rates; lower plasma triiodothyronine and glucose; higher plasma nonesterified fatty acids and beta-hydroxybutyrate; lower intakes of dry matter, net energy for lactation, and crude protein; higher water intakes; and lower body condition scores. The decline of plasma immunoglobulins (Ig) over the final 2 wk of pregnancy was less pronounced for heifers under heat stress. For the first four milkings, colostrum of cows exposed to high air temperatures had lower mean concentrations of IgG and IgA; lower mean percentages of total protein, casein, lactalbumin, fat, and lactose; lower contents (grams per liter) of short- and medium-chain fatty acids; lower energy; lower titratable acidity; and higher pH. Thus, high air temperatures during late pregnancy and the early postpartum period markedly affected the composition of colostrum from primiparous dairy cows.
authors.affiliation: Istituto di Zootecnia, Università della Tuscia, Viterbo, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Nardone
authors.forename: N
authors.initials: N
authors.lastname: Lacetera
authors.forename: U
authors.initials: U
authors.lastname: Bernabucci
authors.forename: B
authors.initials: B
authors.lastname: Ronchi
mesh_terms: D020155:3-Hydroxybutyric Acid; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001831:Body Temperature; D002417:Cattle / Q000502:physiology*; D003126:Colostrum / Q000737:chemistry*; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006885:Hydroxybutyrates / Q000097:blood; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007774:Lactation; D007785:Lactose / Q000032:analysis; D008055:Lipids / Q000032:analysis; D049590:Postpartum Period; D011247:Pregnancy; D012119:Respiration
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D006885:Hydroxybutyrates; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D008055:Lipids; D007785:Lactose; D020155:3-Hydroxybutyric Acid