title: High growth rate fails to enhance adaptive immune responses of neonatal calves and is associated with reduced lymphocyte viability.
abstract: The objective of the study was to evaluate the effects of 3 targeted growth rates on adaptive (i.e., antigen-specific) immune responses of preruminant, milk replacer-fed calves. Calves (9.1 +/- 2.4 d of age) were assigned randomly to one of 3 dietary treatments to achieve 3 targeted daily rates of gain [no growth (maintenance) = 0.0 kg/d, low growth = 0.55 kg/d, or high growth = 1.2 kg/d] over an 8-wk period. The NRC Nutrient Requirements of Dairy Cattle calf model computer program was used to estimate the milk replacer intakes needed to achieve target growth rates. All calves were fed a 30% crude protein, 20% fat, all-milk protein milk replacer reconstituted to 14% dry matter. Diets were formulated to ensure that protein would not be limiting. All calves were vaccinated 3 wk after initiation of dietary treatments with Mycobacterium bovis, strain bacillus Calmette-Guerin and ovalbumin. Growth rates for no-growth (0.11 kg/d), low-growth (0.58 kg/d), and high-growth (1.16 kg/d) calves differed throughout the experimental period. Blood glucose concentrations in high-growth calves increased with time and were higher than in low- and no-growth calves. Mononuclear and polymorphonuclear leukocyte percentages in peripheral blood were unaffected by growth rate but did change with advancing age. Percentages of CD4(+) T cells increased with age in no-growth and low-growth calves, a characteristic of maturation, but failed to increase in high-growth calves. Growth rate did not affect the percentages of CD45RO(+) (memory) CD4(+) and CD8(+) T cells, antigen (i.e., ovalbumin)-specific serum IgG concentrations, or antigen (i.e., purified protein derivative)-induced IFN-gamma and nitric oxide secretion by mononuclear cell cultures. Antigen-elicited cutaneous delayed-type hypersensitivity responses of no-growth calves exceeded responses of low-growth, but not high-growth, calves. In resting- and antigen-stimulated cell cultures, viabilities of CD4(+), CD8(+), and gammadeltaTCR(+) T cells from high-growth calves were lower than those of the same T cell subsets from no-growth and low-growth calves. Alternatively, resting cultures of mononuclear leukocytes from high-growth calves produced more nitric oxide than those from no-growth and low-growth calves. In conclusion, adaptive immune responses were affected minimally by growth rate. The results suggest that protein-energy malnutrition in the absence of weight loss is not detrimental to antigen-specific responses of neonatal vaccinated calves and that a high growth rate does not enhance these responses. The negative effect of a high growth rate on the viability of circulating T cell populations may influence infectious disease resistance of the calf.
authors.affiliation: Nutritional Physiology Group, Department of Animal Science, Iowa State University, 313 Kildee Hall, Ames 50011, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Foote
authors.forename: B J
authors.initials: BJ
authors.lastname: Nonnecke
authors.forename: D C
authors.initials: DC
authors.lastname: Beitz
authors.forename: W R
authors.initials: WR
authors.lastname: Waters
mesh_terms: D000276:Adjuvants, Immunologic / Q000627:therapeutic use; D000704:Analysis of Variance; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D000831:Animals, Newborn; D001500:BCG Vaccine / Q000276:immunology / Q000627:therapeutic use; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight / Q000276:immunology; D002417:Cattle / Q000254:growth & development* / Q000276:immunology*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006968:Hypersensitivity, Delayed / Q000662:veterinary; D007074:Immunoglobulin G / Q000097:blood; D007371:Interferon-gamma / Q000378:metabolism; D007962:Leukocytes / Q000166:cytology* / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000276:immunology; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D010047:Ovalbumin / Q000276:immunology; D013997:Time Factors; D014611:Vaccination / Q000662:veterinary
chemical_list: D000276:Adjuvants, Immunologic; D001500:BCG Vaccine; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007074:Immunoglobulin G; D009569:Nitric Oxide; D007371:Interferon-gamma; D010047:Ovalbumin