Effect of grazing system, stocking rate and season of use on herbage intake and grazing behaviour of stocker cattle grazing alfalfa-grass pastures

Abstract

. 1997. Effect of grazing system, stocking rate and season of use on herbage intake and grazing behaviour of stocker cattle grazing alfalfa-grass pastures. Can. J. Anim. Sci. 77: 677-682. An experiment was conducted to determine the effects of grazing system (continuous and rotational), stocking rate (light, 1.1 steers ha -1 ; heavy, 2.2 steers ha -1 ) and season of use on forage intake and grazing behaviour of stocker cattle grazing an approximately 70% alfalfa (Medicago sativa L.), 25% meadow bromegrass (Bromus biebersteinii Roem & Schult.) and 5% Russian wildrye (Psathyrostachys juncea (Fisch.) Nevski) pasture. To determine organic matter intake, grazed herbage was collected with esophageal fistulated cattle and analyzed for in vitro digestible organic matter while fecal output was determined using chromic oxide. These variables were used to calculate organic matter intake. Daily herbage consumption (g OM kg BW -0.75 d -1 and kg OM d -1 ) did not differ (P > 0.05) for either grazing system or stocking rate from 1991 to 1993, with the exception of greater (P < 0.05) intakes at light compared with heavy stocking rates (10.9 vs. 8.4; kg OM d -1 ) late in the 1991 season. Grazing time was usually lower (8.9 vs. 10.3 h (3-yr mean); P < 0.05) in lightly than in heavily stocked pastures. As available herbage increased, cattle spent less time grazing (y = 12.46 -0.00103 x; r = 0.48, RSD = 2.04, P < 0.001; where y = grazing time and x = herbage mass). Biting rates ranged from 28 to 32 bites min -1 , regardless of year, season, grazing system or stocking rate. Rate of intake (g OM kg -1 BW 0.75 h -1 ) did not differ (P > 0.05) for either grazing system, although it tended to be greater (P < 0.10) at light than at heavy stocking rates. As animals in lightly stocked pastures spent less time grazing, herbage was consumed at an increased rate, which was reflected in increased average daily gain (y = 0.28 + 0.067 x; r = 0.86, RSD = 0.14, P < 0.001; where y = daily gain and x = intake rate). Our results suggest that daily herbage consumption was not affected by grazing system or stocking rate; however, at lower stocking rates, grazing time declined and intake rate tended to increase. . Pour la mesure de la prise de matière organique, l'herbe ingérée était prélevée sur des bovins munis de fistules oesophagiennes et analysée sur la teneur en matière organique (m.o.) digestible in vitro, tandis que les excréments étaient mesurés à l'acide chromique. La consommation d'herbage journalière (g m.o. kg PV 0,75 j -1 et kg m.o. j -1 ) était sensiblement la même quels que soient le système pastoral ou le taux de chargement de 1991 à 1993 sauf qu'en fin de saison 1991, elle était plus forte (P < 0,05) au taux de chargement léger qu'à celui de chargement lourd, soit 10,9 contre 8,4 kg m.o. j -1 . Le temps de broutage était d'ordinaire également plus court (8,9 contre 10,3 h, moyenne de 3 ans, P < 0,05) au taux de chargement léger et à mesure que l'herbe devenait plus abondante, les bêtes passaient moins de temps à brouter (y = 12,46 -0,0...

Effects of Herbage Allowance on Dry Matter Intake, Efficiency of Grazing,Milk Yield and Grazing Behaviour of Crossbred Holstein-Jersey Dairy Cows Grazing Alfalfa Pastures

“…Grazing time increased at the higher of two SR for steers grazing alfalfa pastures [35] and steers grazing tall fescue [36]. Consistent with these studies, grazing time increased by 26 minutes/day as HA decreased from 14.3 to 10.3 kg DM/cow/day in the present study (Table 4).…”

Impact of pasture type on methane production by lactating beef cows

“…Differences between confined, chamber-fed animals consuming conserved feedstuffs and grazing animals, in terms of feeding behavior and rumen digestion kinetics, may be expected as animals on pasture may have higher voluntary intake and rate of passage than chamber-fed animals because they frequently consume less-mature feedstuffs. Pastured animals may also graze for extended periods of time, which may total as much as 8-12 h per day (Popp et al 1997). Johnson et al (1994a) described a technique for measuring CH 4 production by cattle using an inert tracer gas source placed in the rumen of the animal.…”

Predicted methane emissions and metabolizable energy intakes of steers grazing a grass/alfalfa pasture and finished in a feedlot or at pasture using the GrassGro decision support tool

“…Popp et al (1997c) reported that grazing time was 0.9 to 2.04 h d -1 greater for steers at the high compared with the low stocking rate, which suggests that more energy may be expended by steers grazing at high stocking rates. However, Popp et al (1997c) also reported that the intake of organic matter was 0.7 to 1.32 kg d -1 greater for steers grazing at low compared with high stocking rates and this does not conform to the data presented by McCaughey et al (1997). While the possibility of errors in the prediction of DMI by GrassGro cannot be excluded, the evidence suggests that predicted DMI conforms to expected results while those obtained in the field experiment did not.…”

“…In addition, although McCaughey et al (1997) used four steers per treatment replication for the estimation of fecal output, they used only one steer fistulated at the esophagus for the collection of herbage from each treatment replication in order to determine diet digestibility, and possible limitations associated with this protocol have been discussed previously (Cohen et al 2003). However, the importance of these errors is reduced when intake is being estimated for comparative purposes such as in the experiments of Popp et al (1997c) and McCaughey et al (1997).…”