A phenotypic characterization of Rarámuri Criollo cattle introduced into the Southwestern United States

Our objective was to describe key phenotypic characteristics of a population of Rarámuri Criollo (RC) cattle introduced from the Copper Canyon of Chihuahua, México into the Southwestern United States almost two decades ago. We recorded 26 phenotypic traits of 37 RC individuals including mature cows, first-calf heifers, and mature bulls raised at the USDA-ARS Jornada Experimental Range in southern New Mexico. This herd of RC cattle exhibited intermediate body sizes compared to the smaller Corriente and larger Texas Longhorn and Florida Cracker cattle. Coat colors were similar to those described for other Criollo biotypes but horn shape and size of RC appear to be different than that of other US-based Criollo breeds. Though smaller than commercial beef breeds, RC cattle appear to be well-matched to the Southwestern US environments as evidenced by previous studies that evaluated their grazing behavior, weight gains, and carcass quality. Rarámuri Criollo cattle are a genetic resource whose conservation could be critically important for climate change adaptation of ranches in the desert Southwest.

Protein Supplementation and Grazing Behavior for Cows on Differing Late-Season Rangeland Grazing Systems

The objective was to determine if low- or high-residual feed intake (LRFI or HRFI, n = 24 for each) Hereford × Angus cows on continuously or rotationally grazed rangeland altered their grazing behavior when provided a protein supplement in late autumn. Treatments included continuously grazed, control (CCON, n = 12); continuously grazed, supplemented (CTRT, n = 12); rotationally grazed, control (RCON, n = 12); and rotationally grazed, supplemented pastures (RTRT, n = 12). Cows in each treatment had grazing time (GT), resting time (RT), and walking time (WLK) measured for 2 years with accelerometers. Bite rate (BR) was also measured. Time distributions of GT and RT differed by year (p < 0.05), being influenced by colder temperatures in 2016. Cattle in 2016 spent more time grazing during early morning and late evening (p < 0.05) and rested more during the day (p < 0.05). In 2017, cattle in the CCON treatment walked more (p < 0.05) during early morning time periods than did the CTRT cattle, indicative of search grazing. All supplemented cattle had greater BR (p < 0.05) than control cattle in 2017. Cattle with increased nutritional demands alter grazing behavior in a compensatory fashion when grazing late-season rangelands.

Factors Influencing Grazing Behavior by Using the Consciousness-Context-Behavior Theory—A Case Study from Yanchi County, China

Grazing behavior is a key factor that affects the sustainable development of the grassland social-ecological system. Grazing behavior is not only restricted by policies but also affected by the awareness of the herder of the grassland environment. To explore the influencing factors and mechanism behind grazing behavior, Yanchi County of Ningxia, a typical area of the “returning grazing land to grassland” project in Northwest China, was selected as a study area. Based on the consciousness-context-behavior theory, a questionnaire was designed, and 305 households were surveyed. Analysis of structural equation model results show: (1) the environmental sensitivity of herders and their satisfaction with the compensation mechanism regulated grazing behavior. When herders were more dependent on grassland, they were more willing to graze. (2) The grassland dependence, environmental sensitivity of herders, and herders’ satisfaction with the compensation mechanism had a significant interaction effect on grazing behavior. (3) Family livelihood diversification and the number of young and middle-aged laborers had a significant moderating effect on grassland dependence and grazing behavior. These findings are of vital importance for the government to formulate policies to promote the sustainable development of grasslands.

Grazing behavior and winter phytoplankton accumulation

Recent observations have shown that phytoplankton biomass increases in the North Atlantic during winter, even when the mixed layer is deepening and light is limited. Current theories suggest that this is due to a release from grazing pressure. Here we demonstrate that the often-used grazing models that are linear at low phytoplankton concentration do not allow for a wintertime increase in phytoplankton biomass. However, mathematical formulations of grazing as a function of phytoplankton concentration that are quadratic at low concentrations (or more generally decrease faster than linearly as phytoplankton concentration decreases) can reproduce the fall to spring transition in phytoplankton, including wintertime biomass accumulation. We illustrate this point with a minimal model for the annual cycle of North Atlantic phytoplankton designed to simulate phytoplankton concentration as observed by BioGeoChemical-Argo (BGC-Argo) floats in the North Atlantic. This analysis provides a mathematical framework for assessing hypotheses of phytoplankton bloom formation.

175 GPS Tracking Collars and Accelerometers Provide Detailed Tracking of Foraging Behavior and Space Use in Grazing Steers in Bermudagrass and Tall Fescue Pasture

Previous research in feedlot studies has demonstrated that cattle feeding behavior is driven by internal metabolic processes and external environmental stimuli and serves as an indicator of animal health, nutritional status, and growth and feed quality and availability. However, technology has only recently allowed measurement of foraging behavior in grazing cattle. Objectives of this study were to measure frequency and duration of foraging bouts, meals, and total distance traveled during meals in grazing steers. The study was conducted as part of a larger grazing study on a 10-hectare Bermudagrass and Tall Fescue pasture, overseeded with Annual Ryegrass, located at the HH Leveck Animal Research Center, Mississippi State, MS. Using tri-axial accelerometers and GPS information from 10 crossbred steers, we examined foraging and meal bout frequency and duration and distance and speed traveled per meal for the period of March 2019. Observed animal behavior was used to train a randomforest model to predict foraging behavior, with model accuracy and sensitivity of 0.95 and 0.93, respectively. We found individual foraging bouts occurred on average 2,849 bouts per day and took on average 5.0 ± 1.8 min (range: 3–9 min), and that steers fed on average 205 ± 52.8 min/day (range: 120–270 min/day). Steers had an average of 9.5 ± 2.9 meals/day, that took on average, 89.3 ± 93.9 min/meal (range: 0.5–938.5 min/meal). Steers traveled an average of 412.4 ± 93.9 meters per meal, with an average foraging speed between 0 and 0.63 m/s. Traveling distance while foraging was positively correlated with meal length (0.83, P &lt; 0.01) and foraging speed (0.70, P &lt; 0.01). These results show that cattle grazing behavior can be accurately quantified in grazing cattle and warrants further research to examine associations between animal efficiency and performance, forage quality, and pasture management.

PSI-18 Identifying genetic variants associated with grazing, walking, and slope use of cattle experiencing mild heat load

Rangeland is a valuable resource that can allow producers to cost effectively provide nutrients for grazing cattle. However, grazing behavior of cattle is adversely affected when the temperature humidity index is greater than 72. It is possible to select cattle that exhibit efficient grazing behavior even under mild heat stress. This study evaluated genetic associations with grazing behavior to help producers identify cows that will effectively use their rangeland pastures. Using genome-wide associations, this study identified single nucleotide polymorphisms (SNPs) associated with grazing time, walking time and max slope that cattle utilized while experiencing mild heat load. Data were collected from Angus X Hereford 2-year-old beef cows from UI herd over two years (37 grazing and walking minutes, 38 max slope). Genotypes were obtained using a Bovine GGP 50K SNP marker array and 41,686 markers were used in the analyses. Two SNPs on chromosome 11 are significantly (P = 5.01e-7, P = 6.46e-7) associated with grazing minutes and explain 0.52 proportion of variance (PVE). A SNP on chromosome 3 is significant for walking minutes (P=1.91e-6) with a PVE of 0.48. Additionally, a SNP on chromosome 14 is significantly (P = 8.50e-6) associated with max slope and has a PVE of 0.43. This ongoing project identified significant associations with grazing and walking minutes and maximum slope. This research will be strengthened with the addition of more animals over successive years. Some cattle spend more time grazing, walking, or at a higher elevation in mild heat load. Identifying genetic variants associated with grazing time, walking time, and maximum slope use while under heat stress can enable producers to select for cattle that best fit the rangeland available to them.

186 Have New Feeding Technologies Revolutionized the Way We Design Grazing Experiments?

New technologies have enabled autonomous measurement of intake and feeding behavior of pen-fed animals and this has piqued interest in utilizing similar technologies in grazing experiments. Various feeding systems are currently available, but individual supplementation and feeding experiments have been conducted for years using individual feeding stanchions, which are the lowest level of technology for measuring supplement intake. These experiments are laborious as they require animals to be trained and acclimated, gathered at each feeding, and sorted into individual stalls for supplementation—thereby disrupting the animals grazing activities. In the mid-1980s Calan Gate systems (American Calan; Northwood, NH) became popular in pasture supplementation experiments, but still have many of the same disadvantages. Newer, more automated systems, reduce labor and possibly have less disruption of the animal’s grazing behavior, but are reliant on the animal’s willingness to use the system and ability to access it when more dominant peers are present. Individuals also do not always follow the “averages”-based rules we often hold true and behave differently in groups. Recent research with automatic feeders show steers consumed average of 60% of the potential supplement with supplement intake CVs of 50 to 100%. These technologies lead many to question the paradigm of experimental units in experimental designs. The experimental unit is defined as the smallest independently assigned unit to which the treatment is applied. This definition of experimental unit is somewhat limiting when taken to the extreme, but still applies well for experiments utilizing individual animal feeding, regardless of the level of technology involved. In many cases where the aforementioned technologies are used, the individual animal can be both the observational and experimental unit. This symposia presentation will discuss attributes of different feeding options and the implications on study design, experimental power, and the designated experimental unit.

275 Access to Shade Mitigate Heat Stress and Improves Growth Performance in Lambs During Summer

The objective of the present study was to investigate the effects of provision of shade on behavior, physiology, and growth of Merino lambs exposed to natural Australian summer conditions. Sixty Merino lambs were randomly allocated to either pasture with shade (n = 30;paddock with trees) or a pasture without shade (n = 30;paddock without any trees) for one month during southern-Australian summer (February-2021). Sheep were grazing on the pastures as per standard protocols followed on the farm with ad libitum access to water. Lambs were monitored twice daily between 0900-1000h and 1400-1600h to record their behavior, and physiological parameters were recorded on hot days (environmental temperature (T) &gt;30°C). Behavioral patterns were represented as the proportion of animals doing specific activities in each treatment group. Grazing was the most frequent activity observed in animals during morning measurement (&gt; 60% in both groups). However, high temperature (T &gt; 30°C) decreased grazing behavior in sheep to &lt; 5% in both treatments. Standing behavior was significantly greater (65.2 vs 21.6%; P &lt; 0.05) for animals under non-shade treatment, while lying behavior was more frequent (17.3 vs 76.3%; P &lt; 0.01) in animals having access to shade. Significantly more animals were seeking water troughs (P &lt; 0.05) in the non-shade group (33.2%) compared to the shade group (10.3%). On an average hot day (T &gt;28°C), most lambs in the shade group were seeking shade (P &lt; 0.01), and when the temperature exceeded &gt;32°C, 90% of the lambs were seeking tree shade. Sheep with access to shade exhibited lower (P &lt; 0.01) respiration rate (117breaths/min) and rectal temperature (39.7°C) than non-shade group (151breaths/min;40.2°C). Overall, access to shade improved (P &lt; 0.001) average daily gain (+0.047kg/day) in sheep compared to the non-shade group (-0.028kg/day). In conclusion, our research confirms that providing access to shade is an effective ameliorative strategy to mitigate heat-stress in sheep during summer heatwaves.