Behavioural Indicators of Intra- and Inter-Specific Competition: Sheep Co-Grazing with Guanaco in the Patagonian Steppe

In extensive livestock production, high densities may inhibit regulation processes, maintaining high levels of intraspecific competition over time. During competition, individuals typically modify their behaviours, particularly feeding and bite rates, which can therefore be used as indicators of competition. Over eight consecutive seasons, we investigated if variation in herd density, food availability, and the presence of a potential competitor, the guanaco (Lama guanicoe), was related with behavioural changes in domestic sheep in Chilean Patagonia. Focal sampling, instantaneous scan sampling, measures of bite and movement rates were used to quantify behavioural changes in domestic sheep. We found that food availability increased time spent feeding, while herd density was associated with an increase in vigilant behaviour and a decrease in bite rate, but only when food availability was low. Guanaco presence appeared to have no impact on sheep behaviour. Our results suggest that the observed behavioural changes in domestic sheep are more likely due to intraspecific competition rather than interspecific competition. Consideration of intraspecific competition where guanaco and sheep co-graze on pastures could allow management strategies to focus on herd density, according to rangeland carrying capacity.

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.

Performance and Feeding Behavior of Holstein and Holstein × Gyr Crossbred Heifers Grazing Temperate Forages

This study aimed to investigate the difference between Holstein and Holstein x Gyr breeds on feeding behavior and performance of heifers grazing temperate pasture. The experiment was carried out in 89 days, split into 14 days of adaptation and 3 periods of 25 days. Two treatments were used: Holstein (HOL; n = 7) and Holstein × Gyr (HG; n = 7). Heifers grazed a consortium of ryegrass and Bristle Oats and were supplemented individually daily with corn meal at 0.33% of body weight plus 5 kg/d of corn silage. For 3 consecutive days, feeding behavior was observed for individual animals from direct visual observation recording at 10 min intervals. The digestibility trial was performed on d16 to d24 of each period. Body measurements and weight were taken at d0 and at d23, 24, and 25 of each period. Grazing duration, grazing frequency, and bite rate were greater for HOL than HG. Rumination characteristics, intake, digestibility, body measurements were not affected by breed. Breeds had differences in grazing characteristics, but it did not influence performance or intake parameters. Therefore, HOL and HG heifers managed under temperate pasture in tropical countries have similar performance.

Ingestive behavior of Girolando heifers in integrated crop, livestock (ICL), and forestry (ICLF) systems

ABSTRACT Aiming to compare integrated crop, livestock (ICL) and forest (ICLF) systems in relation to ingestive behavior of dairy heifers, a 2 × 2 crossover trial was conducted with two periods and two systems. Eight Girolando (3/4holstein × 1/4 Gyr) heifers were evaluated in pasture of Xaraés palisade grass (Urochloa brizantha ‘Xaraes’ syn Brachiaria brizantha) managed with intermittent stocking. The ICLF systemhad eucalyptus trees planted in tiers with 65% crown cover. Ingestive behavior parameters were obtained using acoustic data collected with mP3 recorders for 48hours. Statistical analysis was performed using the mixed procedure of SAS, and means were compared using the Tukey-Kramer test at 5% significance. The dry mater intake (DMI), number of daily grazing sessions, and the duration of the grazing sessions did not differ (P<0.05) between systems. A higher (P<0.05) bite rate and total daily bites and lower (P<0.05) bite mass was observed in the ICLF system in relation to ICL. Heifers in shaded pasture change their ingestive behavior in comparison with those in full-sun pasture.

Grazing behavior and production for lactating cows differing in residual feed intake while grazing spring and summer rangeland

The objectives were to determine if previously classified, efficient (LRFI, low-residual-feed intake, n = 12 x 2 yr) vs inefficient (HRFI, high-residual-feed intake, n = 12 x 2 yr) lactating 2-yr-old Hereford x Angus cows differed in grazing behavior, body weight (BW), body condition score (BCS), and calf weaning weight while grazing rugged rangeland pastures. Cows were fitted with grazing halters containing both an accelerometer and a global-positioning-system (GPS) data logger during 14 June to 4 July 2016, 2 to 25 August 2016, 23 May to 12 June 2017, and 5 to 28 August 2017. GPS data were recorded at 7-min intervals in 2016 and 4-min intervals in 2017 and accelerometer data recorded at 25 times/s. Grazing time, resting, walking, bite rate, daily travel distance, elevation, and slope were analyzed with a mixed model that included fixed effects of RFI group, day, and RFI group x day and cow within treatment as the random effect. Cow BW, BCS, and calf weaning weight were analyzed by ANOVA with treatment as the main effect. There were no differences (P &gt; 0.10) due to RFI detected for BW, BCS, or calf weaning weights. During periods of mild heat load (MHL), HRFI cows spent more (P &lt; 0.05) time resting during the day at lower elevations (P &lt; 0.05) than LRFI cows. During a 6-d period in spring with only 2 h MHL, HRFI cows grazed 1.7 h/d longer than LRFI cows (P &lt; 0.05); commencing grazing earlier in the morning and extending the grazing bout later. During the summer with &gt; MHL, LRFI cows grazed more than HRFI cows 18% of the time (P &lt; 0.10). The HRFI cows had greater grazing time than LRFI cows only 3% of the time (P &lt; 0.10) during summer. There was no difference (P &gt; 0.10) in bite rate between HRFI and LRFI cattle. The daily travel distance tended (P &lt; 0.10) to be greater for LRFI cattle during summer 2017. Over all sample periods, HRFI had greater walking than LRFI 15% of the time and LRFI exceeded HRFI cattle for walking 3% of the time (P &lt; 0.10). The greater walking for HRFI was assumed to be associated with more search grazing. Metabolic heat load on hot summer days for HRFI cattle is presumed to have contributed to differences observed in grazing behavior. These results suggest that lactating cows with low RFI phenotypes appear to be better adapted to grazing rugged rangelands in late-summer during periods of mild heat load.

Sheep and goat feeding behavior profile in grazing systems

Feeding behavior analysis provides information about the relationships between animals and pastures. Therefore, this review aims to describe some aspects of the feeding behavior profiles of both sheep and goats in grazing systems. The structure of the pasture is a key factor in the feeding behavior of grazing animals. The amount of feed consumed in a given period of time is affected by the number of meals, duration and velocity of swallowing, changes in grazing time, bite rate, bite weight, and quality of ingested forage. The different phenological stages of forage also influence the animals’ strategies to optimize their intake, which consequently changes their behavioral activities. Sheep and goats tend to be more selective than cattle, and young animals are more selective than older animals; this selectivity characteristic is one of the most important aspects to be observed in pasture management. According to the degree of selectivity, the animals will intake forages of higher or lower nutritive quality. In addition, the intensity and distribution of their daily activities (grazing, ruminating, and resting) are influenced by several factors, such as the availability and nutritive value of the pasture, its management, the animal activity in the group, and the predominant climatic conditions of the region.

Supplementation of Growing Beef Heifers With Starch or Highly Digestible Fiber Supplements

Producers are interested in cost-effective forage-based heifer development programs with supplemental feeding, if needed, of a single supplement (reducing the cost of mixed rations) so that it would meet their nutrient requirements. For three consecutive years, the effect of two levels of ground corn (GC) and soybean hulls pellets (SB), were evaluated on performance and grazing behavior of 90 replacement beef crossbred heifers (BW = 235&plusmn;17 kg; average of 10.8 months of age) grazing annual ryegrass (Lolium multiflorum; cv. &lsquo;Nelson&rsquo;) at low stocking rate. Treatments were: 1) no supplementation (CON); 2) 0.5% BW of ground corn (GC05); 3) 0.5% BW of soybean hull pellets (SB05); 4) 1% BW of ground corn (GC1); and 5) 1% BW of soybean hull pellets (SB1). Lower levels of supplements (0.5% BW) allowed for greater (P &lt; 0.05) ADG (1.26 and 1.21 kg for GC05 and SB05, respectively), production per hectare and lower age and BW at puberty. Ground corn or SB at 1% BW negatively affected (P &lt; 0.05) growth (0.88 and 0.95 kg, respectively), reproductive performance, number of steps, and grazing time (329 and 354 minutes, respectively) of heifers. Patch grazing time and bite rate were affected (P &lt; 0.05) by grazing period due to changes in nutritive value of annual ryegrass and search for newly grown green leaves. Beef replacement heifers stocked at a low stocking rate with no supplementation may have a better development when compared to 1% BW supplementation using GC or SB and similar to a 0.5% BW supplementation level.

Stimulation of Insect Herbivory by Elevated Temperature Outweighs Protection by the Jasmonate Pathway

Rising global temperatures are associated with increases in the geographic range, population size, and feeding voracity of insect herbivores. Although it is well established that the plant hormone jasmonate (JA) promotes durable resistance to many ectothermic herbivores, little is known about how JA-mediated defense is influenced by rising temperatures. Here, we used the Arabidopsis-Trichoplusia ni (cabbage looper) interaction to investigate the relative contribution of JA and elevated temperature to host resistance. Video monitoring of T. ni larval behavior showed that elevated temperature greatly enhanced defoliation by increasing the bite rate and total time spent feeding, whereas loss of resistance in a JA-deficient mutant did not strongly affect these behaviors. The acceleration of insect feeding at elevated temperature was not attributed to decreases in wound-induced JA biosynthesis, expression of JA-responsive genes, or the accumulation of defensive glucosinolates prior to insect challenge. Quantitative proteomic analysis of insect frass, however, provided evidence for a temperature-dependent increase in the production of T. ni digestive enzymes. Our results demonstrate that temperature-driven stimulation of T. ni feeding outweighs the protective effects of JA-mediated resistance in Arabidopsis, thus highlighting a potential threat to plant resilience in a warming world.

Pre-Grazing Herbage Mass Affects Grazing Behavior, Herbage Disappearance, and the Residual Nutritive Value of a Pasture during the First Grazing Session

During the first hours after the allocation of a grazing strip (first grazing session, GS), dairy cows eat most of the daily dry matter (DM) available. There are few studies that analyze how the grazing-down process changes the characteristics of the pasture during the first GS. The objective of this study was to evaluate the effect of two pre-grazing herbage masses (HM; medium herbage mass (MHM) and high herbage mass (HHM) on the DM disappearance, grazing behavior of dairy cows, and the residual nutritive value of a pasture during the first GS. Two groups of twelve dairy cows were used to evaluate the grazing-down process, during a period of 62 days. The pre-grazing HM modified the bite rate, bite mass, and dry matter intake during the first GS. The pre-grazing HM affected the process of herbage disappearance of the pasture, especially during the first 60 min of the GS. The nutrient selection differential for acid detergent fiber was greater for HHM compared with MHM (0.93 vs. 0.86). In conclusion, pre-grazing HM affects the structural characteristics and the residual nutritive value of the pasture. The grazing process in the first GS was modified by the HM, affecting the defoliation and the DM disappearance rate of the pasture.