Associations between serum gamma-globulin concentration, enzyme activities, growth and survival in preweaning Alpine goat kids

Colostral immunity is crucial for young ruminants, but the individual factors that may affect passive transfer status and its effects on preweaning growth performance have not been widely investigated in goats. The methods to quantify immunoglobulins G can be expensive. Colostrum enzymes, though, pass the intestinal barrier and might be suitable as markers of passive transfer status, as demonstrated in other ruminant species. This study aimed to investigate the effect of sex, litter size, dam parity, and birth body weight on passive transfer status and the relationship between gamma-globulin concentration (GG) and pre-weaning growth performance in Alpine goat kids. The association between serum GG, serum total protein concentration and serum activity of colostrum enzymes including γ-glutamyltransferase (GGT), alkaline phosphatase (ALP), aspartate aminotrans- ferase (AST), and lactate dehydrogenase (LDH) was examined for their use as predictors of passive transfer status in neonatal goat kids. Sixty-six Alpine goat kids (39 males, 27 females), born to 28 does at one dairy goat farm during two delivery seasons, were enrolled. Kids nursed their dams in group housing until weaned at 50 days of age. Blood samples were collected 24 h after birth. Body weights (BW) were taken at birth and weaning. Serum enzyme activities and total protein concentration were measured using a clinical biochemical analyser. Serum GG was determined by gel electrophoresis. Statistical analysis was performed using GraphPad Prism (v. 8.2.1). No significant differences in serum GG between males and females, singlets and twins, multiparous’ and pri- miparous’ kids were found. No association was detected between birth BW and GG. Serum GG was strongly and significantly associated with TP (R2 =0.85; p 0.0001) and moderately associated with GGT (R2 =0.47; p 0.0001). No correlation was found with ALP, AST, and LDH. Although partial failure of passive transfer (FPT) was diagnosed in 23% of kids, no effects on morbidity (3%), mortality (0%) and pre-weaning growth performance were observed. Our results confirm that serum total proteins can be used to indirectly estimate immunoglobulin concentration. Contrarily, passive transfer status can be predicted with little success by measuring the activity of serum GGT. It is not advisable to use ALP, AST and LDH as indicators of passive transfer status. Finally, FTP is not necessarily associated with the health and preweaning growth performance of Alpine goat kids reared in non- intensive breeding systems that follow good farming practices.