Fasting Plasma Hormones and Metabolites in Feral and Domestic Newborn Pigs

Abstract

Newborn Yorkshire and Ossabaw (feral) pigs were examined under thermoneutral conditions to determine whether survival rate during fasting differs between these breeds and whether any blood-borne factors are associated with improved survival. Newborn pigs were removed from the sow before suckling. Body composition was determined on 10 newborn Ossabaw and 12 newborn Yorkshire pigs. Another group of animals (eight Ossabaw, 12 Yorkshire) was fasted for 72 hr, with blood samples drawn at birth and 12 and 24 hr into fasting. Glucose, free fatty acid (FFA), growth hormone (GH), insulin, thyroxine (T4), triiodothyronine (T3), cortisol and glucagon concentrations were measured in plasma of fasted pigs. Concentrations of carcass lipid, dry matter and ash were higher in newborn Ossabaw pigs than in newborn Yorkshire pigs. Survival through 72 hr of fasting was lower among Yorkshire pigs. Yorkshire and Ossabaw pigs had similar concentrations of metabolites and hormones at birth, with the exceptions of lower plasma GH and higher T3 concentrations in Ossabaw pigs. Higher plasma T3 concentrations would indicate a greater potential for fatty acid oxidation. During fasting, Ossabaw pigs had lower plasma GH and T4 concentrations and higher glucagon and FFA concentrations. Increased survival among newborn Ossabaw pigs may have been due to increased availability of FFA during fasting, and to a greater potential for gluconeogenesis through increased oxidation of fatty acids and higher plasma glucagon concentrations. This would suggest that maternal treatments that would increase storage of fat and(or) increase the capacity for oxidation of fat in utero would improve survival of newborn pigs.

Metabolic differences in hepatocytes of obese and lean pigs

“…Hepatocytes from Iberian had greater glucose production from gluconeogenic precursors (24%, P < 0.05; Figure 1a) than from Landrace pigs although no difference in glycogen degradation between breeds was found (P > 0.10; Figure 1b). In line with our results, greater potential for GNG in Ossabaw compared with Yorkshire pigs has been reported (Kasser et al, 1981). As in the transition from fasted to fed liver glycogen deposition is predominantly a gluconeogenic process in rats (Katz et al, 1986), we could speculate that hepatocytes from Iberian pigs would have greater glycogen synthesis as a result of their increased gluconeogenic capacity compared with Landrace.…”

Serum profile of metabolites and hormones in obese (Iberian) and lean (Landrace) growing gilts fed balanced or lysine deficient diets

“…Furthermore, IGF-1 is expressed in most tissues and can act via an autocrine/paracrine fashion. GH clearly differed when extreme breeds were compared and was mainly lower when a reduced growth rate coincides with high daily deposition of fat (Althen and Gerrits, 1976;Kasser et al, 1981;Wangness et al, 1981). Others found no plasma GH differences among pigs with divergent genetic merit for postweaning ADG (Clutter et al, 1995).…”

Expression of insulin-like growth factor-1 (IGF-1) and growth hormone-receptor (GHR) mRNA in liver, skeletal muscle and adipose tissue of different breeds of pig

“…Porcine genotypes with varying degrees of fatness/ leanness have differing rates of growth and maturation (Haley, d'Agaro and Ellis, 1992;Krick, Roneker, Boyd, Beermann, David and Meisinger, 1992;White, Lan, McKeith, McLaren, Novakofski, Wheeler and Kasser, 1993), and studies on slow growing fat genotypes have indicated differences in plasma IGF-1 and GH levels, when compared with conventional pigs (Buonomo, Lauterio, Baile and Campion, 1987;Lauteric, Trivedi, Kapadia and Daughaday, 1988;Kasser, Martin, Gahagan and Wangsness, 1981;Martin, Ramsay, Campion and Hausman, 1985). On the other hand, plasma IGF-1 and GH levels in two pure extreme breeds, the Large White and Meishan, were shown to be similar when comparing pigs of the same age or pigs at similar stages of sexual maturity (Louveau, Bonneau and Salter, 1991).…”