Effects of dam prepartum supplement level on performance and reproduction of heifer progeny

Objectives were to determine the effect of dam prepartum supplement level on growth performance, feed efficiency and reproductive performance of female progeny (127 heifers in year 1, 138 heifers in year 2). Mature, multiparous, fall-calving, Angus × Simmental cows (initial age = 5.6 ± 1.9 years, BW = 623 ± 70 kg, BCS = 5.7 ± 0.7) were used in a completely randomised design that included three supplement levels: no supplement (NS), low supplement, 2.16 kg·cow−1·d−1 (LS), or high supplement, 8.61 kg·cow−1·d−1 (HS). Cows grazed endophyte-infected tall fescue/red clover pastures and were bunk-fed supplement (70% dried distiller’s grains plus solubles [DDGS] and 30% soybean hulls) 103 ± 11 d prepartum to 2 ± 11 d postpartum. Dam prepartum supplementation did not affect (p ≥ .60) heifer progeny BW at weaning, breeding, nor at pregnancy verification. Dam prepartum supplementation did not affect (p ≥ .18) heifer progeny AI conception rate, overall pregnancy rate, nor calving rate. Calving date, calf birth BW, percentage of unassisted births, milk production and calf BW at 73 ± 16 d of age were not different (p ≥ .24) among heifer progeny, regardless of dam supplement level. In conclusion, these data suggest within a fall-calving, fescue-based production system, supplementing dams with 2.16 or 8.61 kg·cow−1·d−1 of a DDGS-based supplement does not affect growth performance and reproductive performance of subsequent female progeny

Effects of number of animals monitored on representations of cattle group movement characteristics and spatial occupancy.

The number of animals required to represent the collective characteristics of a group remains a concern in animal movement monitoring with GPS. Monitoring a subset of animals from a group instead of all animals can reduce costs and labor; however, incomplete data may cause information losses and inaccuracy in subsequent data analyses. In cattle studies, little work has been conducted to determine the number of cattle within a group needed to be instrumented considering subsequent analyses. Two different groups of cattle (a mixed group of 24 beef cows and heifers, and another group of 8 beef cows) were monitored with GPS collars at 4 min intervals on intensively managed pastures and corn residue fields in 2011. The effects of subset group size on cattle movement characterization and spatial occupancy analysis were evaluated by comparing the results between subset groups and the entire group for a variety of summarization parameters. As expected, more animals yield better results for all parameters. Results show the average group travel speed and daily travel distances are overestimated as subset group size decreases, while the average group radius is underestimated. Accuracy of group centroid locations and group radii are improved linearly as subset group size increases. A kernel density estimation was performed to quantify the spatial occupancy by cattle via GPS location data. Results show animals among the group had high similarity of spatial occupancy. Decisions regarding choosing an appropriate subset group size for monitoring depend on the specific use of data for subsequent analysis: a small subset group may be adequate for identifying areas visited by cattle; larger subset group size (e.g. subset group containing more than 75% of animals) is recommended to achieve better accuracy of group movement characteristics and spatial occupancy for the use of correlating cattle locations with other environmental factors

Maternal Plane of Nutrition during Late Gestation and Weaning Age Alter Angus × Simmental Offspring Longissimus Muscle Transcriptome and Intramuscular Fat.

In model organisms both the nutrition of the mother and the young offspring could induce long-lasting transcriptional changes in tissues. In livestock, such changes could have important roles in determining nutrient use and meat quality. The main objective was to evaluate if plane of maternal nutrition during late-gestation and weaning age alter the offspring's Longissimus muscle (LM) transcriptome, animal performance, and metabolic hormones. Whole-transcriptome microarray analysis was performed on LM samples of early (EW) and normal weaned (NW) Angus × Simmental calves born to grazing cows receiving no supplement [low plane of nutrition (LPN)] or 2.3 kg high-grain mix/day [medium plane of nutrition (MPN)] during the last 105 days of gestation. Biopsies of LM were harvested at 78 (EW), 187 (NW) and 354 (before slaughter) days of age. Despite greater feed intake in MPN offspring, blood insulin was greater in LPN offspring. Carcass intramuscular fat content was greater in EW offspring. Bioinformatics analysis of the transcriptome highlighted a modest overall response to maternal plane of nutrition, resulting in only 35 differentially expressed genes (DEG). However, weaning age and a high-grain diet (EW) strongly impacted the transcriptome (DEG = 167), especially causing a lipogenic program activation. In addition, between 78 and 187 days of age, EW steers had an activation of the innate immune system due presumably to macrophage infiltration of intramuscular fat. Between 187 and 354 days of age (the "finishing" phase), NW steers had an activation of the lipogenic transcriptome machinery, while EW steers had a clear inhibition through the epigenetic control of histone acetylases. Results underscored the need to conduct further studies to understand better the functional outcome of transcriptome changes induced in the offspring by pre- and post-natal nutrition. Additional knowledge on molecular and functional outcomes would help produce more efficient beef cattle

Effects of prepartum plane of nutrition during mid- or late gestation on beef cow body weight, body condition score, blood hormone concentrations and preimplantation embryo

The objectives were to evaluate the potential effect of prepartum plane of nutrition during mid- or late gestation on cow BW, BCS, blood hormone concentrations and preimplantation embryos. In Exp. 1, multiparous Angus and Angus × Simmental cows (n = 33; BW = 664 ± 78 kg) were fed diets formulated to provide three planes of nutrition: 100% NRC energy and protein requirement (REQ), 70% NRC requirement (70%REQ) or 130% NRC requirement (130%REQ) during late gestation (91 ± 4 to 8 ± 4 d prepartum). Cows fed 130% REQ tended to have greater BW (p = 0.06) at breeding, greater progesterone concentrations (p = 0.09), and fewer total embryos recovered at 84 ± 5 d postpartum (p = 0.07) when compared with cows fed REQ. In Exp. 2, multiparous Angus and Angus × Simmental cows (n = 35; BW = 601 ± 72 kg) were fed the same diets as Exp. 1, but were fed during mid-gestation (195 to 112 ± 4 d prepartum). Cows fed REQ and 130% REQ had greater (p = 0.02) BW at breeding when compared with cows fed 70% REQ. Cows fed 70% REQ and 130% REQ during mid-gestation had a greater (p = 0.03) count of total embryos recovered at 86 ± 4 d postpartum when compared with cows fed REQ. In conclusion, while prepartum nutritional treatments tended to affect cow BW and BCS at breeding, effects on embryo production differed depending on the stage of gestation at which nutritional treatments were applied

Geoprocessing workflow for comparing KDE maps of subset groups with the entire herd.

<p>ArcGIS ModelBuilder (ESRI, Redlands, CA) was used to facilitate the spatial comparison of density maps of grazing distributions between subset groups and the entire herd via GPS point data.</p

Comparison of KDE maps between subset groups and the entire herd.

<p>Example of GPS location data of a subset group of size 18 (group A) were converted to a rasterized map, which quantifies the pasture visitation rates by cattle using KDE analysis. White and black areas denote the grazing areas for the herd. Intense white areas are indicative of high cattle visitation rates. The map was further normalized (A) in order to compare with a similar map (B) of the entire herd. A difference map (C) was created to denote the differences between the two maps (pixels with values larger than 0.05 are shown in red, smaller than -0.05 in blue, and others in beige). The same highly visited areas can be identified based on (A) or (B) since they are very similar spatially, as white intense areas on both maps are located around watering and bedding areas.</p

Comparative statistics for error evaluation of spatial occupancy analysis.

<p>The average percentage of cells within difference maps within the error tolerance (|errors|<0.05) increases linearly (<i>r</i>^<i>2</i> = 0.99028) as subset group size increases (A). The average maximum and minimum difference values decreases as subset group size increases (B). Error bars denote ± SE.</p