ABSTRACT:
This study is concerned with an evaluation of the influence of mode of birth on the transfer of passive immunity and some serum constituents to newborn lambs, naturally fed with colostrum, breed in the semiarid region of the State of Paraiba (Brazil) on an extensive system. Thirty-four clinically healthy Santa Ines lambs were employed, identified and weighted immediately after birth, and divided into two experimental groups of seventeen animals each. The PS group (nine males and eight females) included lambs born of single pregnancies and the PG group (six males and eleven females) comprised of lambs born of twin pregnancies. The colostrum intake occurred naturally and voluntarily at their mothers. Forty-eight hours after birth, 10 mL of blood were collected in siliconized tubes from each animal by puncture of the jugular vein, and maintained under vacuum. After centrifugation, aliquots of sera were separated and kept frozen at -15°C until analyzed. For the comparative study of serum constituents, two experimental groups were formed, distributed in a completely randomized lineation, 2x2 factorial (type of birth and sex). The data were subjected to analysis of variance, whose means were compared by Tukey test at 5%. The serum activities of AST and GGT, and the total protein serum, albumin, urea, creatinine, calcium, phosphorus and magnesium concentrations were determined by using sets of commercial reagents; the samples were read by an automatic spectrophotometer. The serum activities of AST, GGT and serum concentrations of total protein, albumin and globulins of the PS and PG lambs groups were not influenced by the type of pregnancy and sex. From the serum concentration of total protein, FTIP was found in the lambs of PG group, using the value of 5.0g/dL as the cutoff point. With the exception of calcium, serum concentrations of urea, creatinine, phosphorus and magnesium showed the same pattern. Although these constituents did not showed significant differences between groups and sex, higher values were observed in animals born of single pregnancies, suggesting that the absence of competition for the voluntary ingestion of colostrum may have been the determining factor. It can be concluded that lambs born twin deliveries and breed extensively in the semiarid region of the State of Paraiba failed to transfer passive immunity and showed significant reduction in serum levels of some biochemical constituents, indicating the need for human interference in these cases.
INDEX TERMS:
Immunity transfer; sheep; newborns; colostrum; serum biochemistry; immunoglobulins