Intestinal development of bovine foetuses during gestation is affected by foetal sex and maternal nutrition
Maternal nutritional restriction from conception to mid‐gestation may decrease foetal intestinal mucosa diameter and area in sheep (Trahair et al., 1997). However, foetuses from cows submitted to nutritional restriction may present greater vascularization and cellular proliferation at the jejunum, and higher relative size of intestine and villi length (Duarte et al., 2013). Moreover, it has been reported that lambs from ewes submitted to nutritional restriction had better immunoglobulin absorption efficiency during the first hours after birth, while lambs from overnourished sheep had reduced immunoglobulin absorption efficiency (Hammer et al., 2011). In many of these cases, the foetal intestinal development changes were suggested as adjustments due to a lower or higher maternal ability to produce colostrum according to the feeding level during pregnancy (Swanson et al., 2008; Hammer et al., 2011; Duarte et al., 2013). Information on the direct effects of maternal feeding plan on the foetal intestinal development independent of colostrum production is lacking. None of the previous studies in cattle (Meyer et al., 2010; Duarte et al., 2013) used dairy cows. Such animals are often subject to different nutritional plans during gestation according to previous lactation and dry periods (Holtenius et al., 2003; Odensten et al., 2005; March et al., 2014) and even then producing significant amounts of colostrum in the post‐natal period (Kessler et al., 2013; Garcia et al., 2014).
In addition to the limited number of studies regarding dietary effects on gastrointestinal development of bovine foetuses, to our knowledge there are no previous studies highlighting foetal sex (FS) differences regarding intrauterine intestinal development. Therefore, we hypothesized that different maternal feeding levels may affect the foetal intestine development of high‐genetic‐merit dairy cattle. From an investigative form, we proposed the FS inclusion as one of the factors involved on an intrauterine development of cattle intestine. Therefore, this study aimed to evaluate maternal feeding level and FS effects on intestinal development of cattle foetuses along different gestation stages.