Development of gastrointestinal tract of newborn goats under maternal feed restriction at different stages of gestation

Abstract

The objective of this study was to elucidate the effect of maternal feed restriction during two distinct phases of gestation (initial half and final half) on the formation of vital organs and growth and development of the small intestine of the offspring. Fourteen pregnant goats were divided into two treatments with different dietary levels, according to the gestation phase. Eight of them were fed 100% of total digestible nutrients (TDN) and crude protein (CP), according to the recommendations of the NRC (2007), in the first half of pregnancy and then received 50% of TDN and CP until parturition date (M-R treatment). The remaining six goats were fed 50% of TDN and CP in the first half of pregnancy and received 100% of TDN and CP in the second half of pregnancy (R-M treatment). Male offspring was separated from the dams at birth and blood samples were collected from these animals. Later, the newborn goats were weighed and slaughtered for collection of corporal components. Maternal feed restriction did not affect the blood glucose concentration, birth weight, organ weights and other body components of the slaughtered offspring (P > 0.13). The weight of reticulum-rumen and omasum did not differ between treatments (P = 0.893), but tended to be heavier (P = 0.057) in the M-R group, when expressed per kg of body weight. The small intestine (P = 0.055) and total intestine (P = 0.095) tended to be heavier in the offspring of the M-R group, and this characteristic was more pronounced (P = 0.038) when expressed in kg body weight. The lengths of the small intestine and total intestine were higher (P ≤ 0.05) in the M-R group, however, no differences were observed in the weight to length ratio of the small intestine and total intestine of the offspring (P > 0.46). Maternal feed restriction also did not influence the height of the intestinal villi (P = 0.406). However, newborn goats of group R-M had lower villus height to crypt depth ratio (P = 0.016), due to the tendency of the greater of crypt depth in these animals (P = 0.081). No effect of maternal feed treatment was observed in the mRNA expression of the MGAM and GLP-2R in the jejunum of the offspring (P > 0.12), but newborns of the M-R group tended to express more mRNA of the SLC5A1 (P = 0.091), SLC2A2 (P = 0.091) and OCLN (P = 0.061). The animals born from single gestation tended to express more MGAM mRNA (P = 0.061) and this effect was more pronounced in the SLC2A2 mRNA expression (P = 0.025), compared to the animals from the twin gestation. In addition, a maternal feed restriction × number of fetuses interaction was observed for LCT mRNA expression (P = 0.043). Singletons of the RM treatment expressed more LCT mRNA compared to the offspring of the M-R (single) and R-M (twin) groups, but no difference was observed when compared to the twins of the M-R group. In general, the results obtained in this study demonstrated that maternal feed restriction at different stages of gestation alters differently the growth and development of the small intestine. Even without changes in body weight and blood glucose levels of newborns, restriction in the first half of gestation may be more detrimental to the performance and health of offspring throughout life, due to increased impairment of intestinal development.