Small-intestinal growth and function are critical for optimal animal growth and health and play a major role in nutrient digestion and absorption, en

As the demand for food increases with exponential growth in the world population, it is imperative that we understand how to make livestock production as efficient as possible in the face of decreasing available natural resources. Moreover, it is important that livestock are able to meet their metabolic demands and supply adequate nutrition to developing offspring both during pregnancy and lactation. Specific nutrient supplementation programs that are designed to offset deficiencies, enhance efficiency, and improve nutrient supply during pregnancy can alter tissue vascular responses, fetal growth, and postnatal offspring outcomes. This review outlines how vascularity in nutrient transferring tissues, namely the maternal gastrointestinal tract, the utero-placental tissue, and the mammary gland, respond to differing nutritional planes and other specific nutrient supplementation regimes.

We hypothesized that gestational nutrition would affect calf feed efficiency and small intestinal biology, which would be correlated with feed efficiency. Multiparous beef cows (n = 36) were individually fed 1 of 3 diets from d 45 to 185 of gestation: native grass hay and supplement to meet NRC recommendations (control [CON]), 70% of CON NE_m (nutrient restricted [NR]), or a NR diet with a RUP supplement (NR+RUP) to provide similar essential AA as CON. After d 185 of gestation, cows were managed as a single group, and calf individual feed intake was measured with the GrowSafe System during finishing. At slaughter, the small intestine was dissected and sampled. Data were analyzed with calf sex as a block. There was no effect (P ≥ 0.33) of maternal treatment on residual feed intake, G:F, DMI, ADG, or final BW. Small intestinal mass did not differ (P ≥ 0.38) among treatments, although calf small intestinal length tended (P = 0.07) to be greater for NR than NR+RUP. There were no differences (P ≥ 0.20) in calf small intestinal density or jejunal cellularity, proliferation, or vascularity among treatments. Jejunal soluble guanylate cyclase mRNA was greater (P < 0.03) for NR+RUP than CON and NR. Residual feed intake was positively correlated (P ≤ 0.09) with small intestinal mass and relative mass and jejunal RNA content but was negatively correlated (P ≤ 0.09) with jejunal mucosal density and DNA concentration. Gain:feed was positively correlated (P ≤ 0.09) with jejunal mucosal density, DNA, protein, and total cells and was negatively correlated (P ≤ 0.05) with small intestinal relative mass, jejunal RNA, and RNA:DNA. Dry matter intake was positively correlated (P ≤ 0.09) with small intestinal mass, relative mass, length, and density as well as jejunal DNA and protein content, total cells, total vascularity, and kinase insert domain receptor and endothelial nitric oxide synthase 3 mRNA and was negatively correlated (P = 0.02) with relative small intestinal length. In this study, calf performance and efficiency during finishing as well as most measures of small intestinal growth were not affected by maternal nutrient restriction during early and midgestation. Results indicate that offspring small intestinal gene expression may be affected by gestational nutrition even when apparent tissue growth is unchanged. Furthermore, small intestinal size and growth may explain some variation in efficiency of nutrient utilization in feedlot cattle.

To determine effects of dam parity on perinatal nutrient availability in beef cattle, data and samples were collected from 18 primiparous and 35 multiparous spring-calving Sim-Angus dams and their calves. Time to stand was recorded and neonatal vigor assessed. Jugular blood was collected from a subset of calves at 0 (post-standing and pre-suckling) 6, 12, 24, 48, and 72 h of age, and blood chemistry panels were completed. Expelled placentas were dissected, dried, and weighed. Prepartum maternal circulating glucose, non-esterified fatty acids (NEFA), triglycerides, and urea N were analyzed. All statistical models included the fixed effect of dam parity, and calf sex (when P ≤ 0.25) was included for calf and placental variables. Effects of sampling hour, and parity × hour were included for calf metabolites over time using repeated measures. Multiparous dams had greater body weight prepartum (P < 0.001) but similar (P = 0.25) body condition score. Maternal circulating urea N and triglycerides were greater (P ≤ 0.05) in multiparous dams pre-calving. Calves born to primiparous dams weighed 10% less (P ≤ 0.04) at birth with smaller (P ≤ 0.01) heart and abdominal girths. Cotyledonary, intercotyledonary, and total placental masses were less (P ≤ 0.05) for primiparous dams. Dam parity did not affect (P ≥ 0.58) calf time to stand, vigor score at 10 min, or rectal temperature. Serum glucose was greater (P = 0.03) at 0 h but less (P ≤ 0.04) at all other hours in calves from primiparous dams. Calves from primiparous dams had greater (P ≤ 0.02) serum NEFA at 6, 12, and 24 h although plasma triglycerides were greater (P < 0.001) at 6 h. Calves from primiparous dams had greater (P ≤ 0.04) serum urea N at 12 h and creatinine at 12 and 24 h. Plasma insulin was greater (P ≤ 0.04) in calves from multiparous dams at 12, 48, and 72 h, but parity did not affect (P ≥ 0.18) serum total protein or plasma cortisol. Serum aspartate aminotransferase was greater (P ≤ 0.04) at 6 and 24 h, creatine kinase was greater at 24 h, and gamma-glutamyl transpeptidase was less (P ≤ 0.04) at 6, 12, and 24 h, for calves from primiparous dams. Calves born to primiparous dams had greater (P ≤ 0.02) total bilirubin and direct bilirubin at 12 and 24 h. Data indicate that calves born to first-parity heifers had decreased perinatal nutrient availability, resulting in reduced fetal and placental growth, as well as greater energy reserve mobilization and metabolic indicators of stress as neonates. Approximately two-thirds of beef calf deaths prior to weaning occur within the first 3 wk after birth. The goal to have heifers produce their first calf by 2 yr of age likely contributes to factors that limit nutrients available for fetuses and calves immediately after birth. However, little is known about differences in heifers (first parity) and cows (later parities) regarding factors affecting calf resilience, such as fetal growth and calf metabolism shortly after birth. Our data show that calves born to first-parity heifers had altered nutrient availability, demonstrated through smaller placentas, lower birth weights, and altered metabolites in early life. Although calves had similar vigor and ability to maintain body temperature, calves born to first-parity heifers had to mobilize more energy and had lower insulin during the first 3 d post-birth. Calves born to first-parity heifers had greater indicators of stress during the first 72 h of life not associated with calving difficulties. Overall, these effects may have increased morbidity and mortality of calves born to first-parity heifers if they were in a less intensively-managed system. Better understanding of challenges faced by calves born to first-parity dams provides opportunities for their improved management.

Changes in locomotor activity of beef females during the 72 h prepartum were determined in 3 experiments: 1) a 2-yr study with spring-calving multiparous cows (Exp. 1; n = 34 and 27 for yr 1 and 2, respectively); 2) spring-calving primiparous (first pregnancy; n = 13) and multiparous (n = 21) dams (Exp. 2); and 3) fall-calving multiparous cows (Exp. 3; n = 33). For all experiments, IceQube activity monitors (iceRobotics, Edinburgh, UK) were placed above the left hind fetlock of pregnant females ≥ 3 d prepartum. During the calving season, females were housed in 18 x 61 m drylots with ad libitum access to hay or haylage. Parturition was closely monitored, and time of birth was noted. Motion index, standing and lying time, step count, and number of lying bouts for each dam (summed per hour) were determined for the 72 h preceding calving. Within experiment, data were analyzed by day (d -3 to d -1 prepartum), by 6-h period during the final 24 h prepartum, and by hour during the final 6 h prepartum using a mixed model with time as a repeated effect. Year was also included as a fixed effect in Exp. 1. Fixed effects of parity and time prepartum x parity were included for Exp. 2. In all 3 experiments, motion index, standing time, step count, and number of lying bouts were greater (P < 0.001) on d -1 compared with d -2 and -3 prepartum. In the 24 h prepartum, dams had greater (P < 0.01) motion index, standing time, step count, and number of lying bouts during 6 h preceding parturition compared with -11 to -6 h in all experiments. Motion index, step count, and lying bouts changed (P ≤ 0.02) during the last 6 h in all experiments. Primiparous dams had more (P ≤ 0.01) lying bouts than multiparous dams during the last day and -11 to -6 prepartum. In all experiments, number of lying bouts more than doubled (P < 0.001) from -2 to -1 prepartum, with no effect of year (P = 0.57) in Exp. 1 or parity (P ≥ 0.29) in Exp. 2. This suggests that lying bout changes may be the most reliable of parameters measured in detection of calving. Moreover, fall-calving cow behavioral patterns were similar to changes observed in spring-calving females, suggesting that calving season may have minimal effects on pre-calving behavior. Overall, electronic locomotor activity monitors can detect behavioral changes peripartum in beef heifers and cows. More research is necessary to determine if these can be used to remotely sense early signs of parturition in beef cattle.