Higher Herbage Mass Research Articles

Influence of pre-grazing herbage mass on bite mass, eating behaviour, and dairy cow performance on pasture.

Knowledge about individual daily herbage dry matter (DM) intake (DMI) helps identifying efficient dairy cows and adapting supplementation better to herbage intake and nutrient requirements of grazing dairy cows. With the aid of behavioural characteristics, raw data recorded with the RumiWatch (RW) system and processed with the RW converter 0.7.3.31 (C31), estimation of herbage DMI may be possible. First, C31, which allows differentiation of prehension bites and mastication chews, was validated through direct observation of behavioural characteristics and compared to the previous RW converter 0.7.3.11 (C11). Further, the influence of a low and high pre-grazing herbage mass (HM), with the same target herbage allowance (HA), on bite mass, DMI, number of prehension bites, and milk production was investigated. In total, 24 lactating Holstein cows were pairwise allotted to one of two HM treatments. The cows received a new pasture paddock twice per day with a daily target HA of 22 kg DM per cow/day. On average, low HM (LHM) and high HM (HHM) paddocks had an HM of 589 and 2288 kg DM/ha, respectively, above 6.7 click units (1 CU = 0.5 cm). Overall, LHM cows produced 2.7 kg/day more milk and 2.5 kg/day more energy-corrected milk, had the same herbage DMI and a similar prehension bite mass. The averaged bite mass per week was 0.49 g DM/bite (LHM) or 0.47 g DM/bite (HHM), respectively. A longer eating time (617 vs. 559 min/day) and a shorter rumination time (297 vs. 365 min/day) were observed for the LHM cows compared with the HHM cows. The validation of the RW showed similar results for C11 and C31 apart from prehension bites, where C31 showed a mean absolute deviation of 12.4%. Pre-grazing HM had no effect on relevant behavioural characteristics for prospective intake estimation, namely, bite mass and number of prehension bites.

Herbage mass of Teosinte (Euchlaena mexicana) grown as mono and mixed with legumes

The popular summer cereal fodder is Teosinte (Euchlaena mexicana) which has low productivity and chemical constituents. The quality and quantity of teosinte fodder can be enhanced by adjusting cultivation practices including use of appropriate sowing dates and by following an appropriate mixed cropping cultivation with legumes. This study was conducted to identify the fodder quantity and quality under a commonly practiced mixed cultivation of legumes with teosinte with varied sowing dates. Three combination of fodder; teosinte, teosinte+cowpea and tesosinte+rice bean was arranged in four sowing dates in Split Plot Design, replicated five times. Sowing dates were arranged as main plot while combination of fodder species was arranged as sub plot. Growth parameters of teosinte (tiller numbers/m2, plant height), green herbage mass, dry herbage mass, crude protein (CP), acid detergent fiber (ADF) and neutral detergent fiber (NDF) were determined. The results showed significantly highest (p<0.05) cumulative green and dry herbage mass was obtained from teosinte+cowpea, if sown in 18th April followed by 28th April for the same combination of treatments. Significantly the highest (p<0.001) average value of CP was obtained from teosinte+cowpea whereas the highest (p<0.001) average value of NDF and ADF were obtained from teosinte mono crop. The effect of date of sowing and treatments interaction/combination on average value of CP, NDF and ADF were statistically similar (p>0.05). The result of this experiment indicated that teosinte sown with cowpea in 18th April might be the best combination to produce high herbage mass as well as better quality of fodder. Bangladesh Journal of Animal Science. 2022. 51 (2): 47-54

Intake, Energy Expenditure and Methane Emissions of Grazing Dairy Cows at Two Pre-Grazing Herbage Masses

A grazing experiment was undertaken to assess the effects of two levels of herbage mass (HM) on herbage DM intake (DMI), fat and protein corrected milk yield (FPCM), grazing behaviour, energy expenditure (HP), and methane emissions (CH4) of grazing dairy cows in spring. Treatments were a low HM (1447 kg DM/ha; LHM) or a high HM (1859 kg DM/ha; HHM). Pasture was composed mainly of cocksfoot (Dactylis glomerata) and lucerne (Medicago sativa), offered at a daily herbage allowance of 30 kg DM/cow, above 5 cm. Eight multiparous Holstein cows were used in a 2 × 2 Latin Square design in two 10-day periods. Despite the differences in pre-grazing HM between treatments, OM digestibility was not different (P = 0.28). Herbage mass did not affect DMI or FPCM. Grazing time was not different between treatments, but cows had a greater bite rate when grazing on LHM swards. However, HP did not differ between treatments. Daily methane emission (per cow), methane emission intensity (per kg FPCM) and methane yield (as percentage of gross energy intake) were not different. The lack of effect of the amount of pre-grazing HM on energy intake, confirms that the difference between HM treatments was beyond the limits that impose extra energy expenditure during grazing.

Threshold values to discriminate grazing activity of dairy cows by an uni-axial accelerometer as affected by grazing season and herbage mass

Recording grazing time is important because the time allocated for each grazing event is one of the limitations to achieving high intake levels. Grazing time can be measured via visual observation or, more recently, by devices calibrated for this purpose. The Kenz Lifecorder Plus (Suzuken Co. Ltda., Nagoya, Japan) has been used to record daily grazing time with high accuracy, but none of the previous studies have analyzed how pasture characteristics and grazing management influence the recording sensitivity of this device. Thus, the aim of this study was to evaluate the effect of pre-grazing herbage mass and season of the year on the activity level recorded by the Lifecorder Plus and its resulting threshold value used to determine a grazing event for dairy cows. A randomized 2 × 2 factorial design was used to evaluate the effect of two pre-grazing herbage masses (HM), medium herbage mass (MHM) and high herbage mass (HHM), in two seasons, winter (WIN) and spring (SPR), on the observed and predicted grazing time. In each period, two groups of six Holstein Friesian cows were fitted with a Lifecorder Plus in a collar attached to their neck. The pasture characteristics and observed and predicted grazing times were measured. There was no effect (P > 0.05) of HM on the observed grazing time. The grazing time in SPR was significantly higher (P < 0.001) than that in WIN. There was no effect (P> 0.05) of HM on the threshold value. The threshold value for SPR was significantly higher (P < 0.001) than that for WIN. The mean relative prediction error of all treatments was 0.07, which implies a precision of 0.93 in grazing detection and demonstrates a high level of precision in the estimation of daily grazing time. Determining an independent threshold value for each treatment was necessary to obtain a high degree of precision in estimating grazing time. In conclusion, changes in the structural sward characteristics caused by grazing management or the annual cycle of growth of the pasture affect both the activity level recorded using a Lifecorder Plus and the threshold value obtained to detect grazing events in dairy cows. When studies incorporate factors that might alter grazing behavior, a specific threshold value for the study conditions needs to be determined to estimate the grazing time of dairy cows with higher precision.

Bark-stripping of African mahogany trees (Khaya spp.) by cattle in silvopastoral systems in Brazil

African mahogany (Khaya spp.) produces high-value wood, and its cultivation is expanding in tropical regions. The silvopastoral system is an alternative method for growing timber trees, but may involve cattle stripping bark from trees, which limits its usefulness. We evaluated cattle bark-stripping rates in two African mahogany species, K. grandifoliola and K. senegalensis, in a silvopastoral system with Guinea grass, Panicum maximum, in South-eastern Brazil. Cattle had free access to plantations of both tree species for 2 weeks in May 2018 and July 2019, when trees were 5 and 6 years old, respectively. In 2018, we found bark-stripping only in K. grandifoliola, but in 2019 both species were bark-stripped. The proportion of bark-stripped trees was higher for K. grandifoliola than for K. senegalensis. Considering both years, 29/155 (18.7%) K. senegalensis trees and 106/153 (69.3%) K. grandifoliola trees had some of their bark-stripped by cattle. Bark-stripped trees had lower trunk diameter growth than unaffected trees, and their growth was affected by the degree of bark-stripping. Some trees were girdled by bark-stripping. These trees dried up, and some of them fell down 1 year after girdling. In 2019, despite the high herbage mass, levels of crude protein in the pasture were very low, which may have stimulated bark-stripping. Although we could not identify the reasons for bark-stripping, we recommend avoiding the use of silvopastoral systems with cattle and African mahogany in times of the year when pasture has a low quality.

Grazing Seasons and Stocking Rates Affects the Relationship between Herbage Traits of Alpine Meadow and Grazing Behaviors of Tibetan Sheep in the Qinghai-Tibetan Plateau.

Simple SummaryThe relationship between vegetation and grazing behavior of Tibetan sheep on the Qinghai–Tibetan Plateau (QTP) remains a major concern for pursuing the sustainable grazing management of grassland. Grazing behavior is the daily activity of grazing livestock, which can reflect the growth status of the pasture and the level of grassland health in the local pasture, as well as the nutritional needs of Tibetan sheep. We studied the relationship between the grazing behaviors of Tibetan sheep and the quantity and quality of forage in different seasons and different stocking rates. Our results showed that the grazing behavior of Tibetan sheep was greatly affected by the quantity and nutritional quality of the forage. These results may be helpful for local herders to evaluate the nutritional status of forage and condition of grassland degradation, so that appropriate measures can be taken to protect local pastures in advance.Under the combined effect of stocking rate and grazing season, it is very significant to ascertain whether there is a quantitative relationship between plant community characteristics, chemical composition of forage, and grazing behaviors of Tibetan sheep to better utilize native pasture in the northeast region of the Qinghai–Tibetan Plateau (QTP). The two consecutive year observation experiments on Tibetan sheep’s grazing behavior were conducted to evaluate the above-stated relationships between stocking rates of 8 sheep/ha and 16 sheep/ha stocking rates in the both the warm and cold seasons. The results demonstrated that at 8 sheep/ha or in the warm season, due to better forage quality, Tibetan sheep had higher herbage mass, forage crude protein (CP) concentration, CP intake, dry matter intake (DMI), and interval between feed boluses and total number of steps, as well as lower fiber concentration than that at 16 sheep/ha or in the cold season. Diurnal intake rate and walking velocity while intaking increased as both average daylight ambient temperature and relative humidity rose. Using the CP concentration, acid detergent fiber (ADF) concentration, neutral detergent fiber (NDF) concentration, and forage metabolic energy (ME) to predict grazing behavior yielded the best fit equation for Tibetan sheep. For local herdsmen to sustainably use the alpine meadow, 8 sheep/ha in the warm season should be considered as the better grazing condition for preventing grassland degradation.

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

Simple SummaryThe progressive defoliation carried out by dairy cows during the grazing-down process affects the characteristics of the pasture, the dry matter intake and the productive performance of the animals, particularly during the first hours of grazing. This is especially relevant when increasing the efficiency in pasture-based dairy systems. Two pre-grazing herbage masses (high and medium herbage masses) were used to evaluate the process of defoliation carried out by dairy cows during the first hours after the beginning of grazing and its effects on the pasture and animals. The pre-grazing herbage mass affected the ingestive behavior of dairy cows, which influenced the productive performance, and the morphological characteristics and nutritive value of the pasture. It is concluded that pre-grazing herbage mass affects the grazing process carried out by dairy cows during the first hours after the allocation of a new grazing area, modifying the eating pattern of the dairy cows. The results of our study allow highlighting the importance of grazing management in pasture-based dairy systems.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.

Morphological adaptations of signal grass in response to liming and cutting severities

Changes in morphological composition and in the plant population were evaluated during late spring, summer and autumn, in swards of Brachiaria decumbens cv. Basilisk in response to liming (C0.0, without liming; C0.7, limestone amount equivalent to 0.7 ton ha-1; and C1.0, limestone amount equivalent to 1.0 ton ha-1), which were subjected to severe or lenient cutting (40 or 60% of the pre-cutting height, respectively). Increased limestone doses did not result in higher herbage mass (HM), leaf area index (LAI) or proportion of leaves (%L) in the pre-harvest. However, lower proportion of dead material was registered in C0.7 treatment. The treatments C0.0 e C0.7 had higher %L during late spring and summer when associated to severe cutting regimes (R40%), although they reached the pre-harvest condition with lower HM and longer regrowth periods compared to lenient cuttings. The Brachiaria decumbens cv. Basilisk modifies its shoot architecture during the growth season, indicating that lower pre-harvest heights are required during autumn. The absence of liming led to a sharp decreasing of base saturation and levels of K, Ca and Mg in the soil. The minimum annual amount of limestone required for B. decumbens correspond to 0.7 ton ha-1.

Longer rest periods for intensive rotational grazing limit diet quality of sheep without enhancing environmental benefits

Intensive rotational grazing systems (also called cell grazing, holistic grazing or time-controlled grazing) are often implemented to improve production and environmental outcomes. Over recent years there has been considerable interpretation and adaption of the holistic principles that guide the management of these systems. In southern Australia, this has led to an increasing use of longer rest periods for intensive rotational grazing. This experiment was established to compare three intensive rotational grazing strategies (fast rotation [FR], average 57-day rest; slow rotation [SR], average 114-day rest; and flexible grazing [FX], based on availability of green herbage mass) with continuous grazing (CG) to assess the impact these systems have on vegetation and diet quality. The grazing treatments were run across three production zones (PZs) in the landscape (low [LPZ], medium [MPZ] and high [HPZ]) to determine whether management by landscape interactions influenced vegetation. Pasture composition was mostly influenced by PZ in the landscape with Microlaena stipoides and Holcus lanatus more prevalent in the HPZ and Rytidosperma spp. more common in the LPZ. The intensive rotational grazing treatments all had greater herbage mass and ground cover than CG. Composition change often occurred in one PZ and not another (e.g. Hypochaeris radicata increased with SR in the LPZ), or there were contrasting effects in different parts of the landscape (e.g. M. stipoides increased with FR compared with CG in the HPZ but decreased in the LPZ). Diet quality was lower for the SR compared with the other grazing treatments. Maintaining a post-grazing benchmark of >0.5 t green DM ha−1 was associated with a higher diet quality. Based on this two-and-a-half-year study run during poor seasons, it can be concluded that intensive rotational grazing can be managed, with fast and flexible rotations, to achieve per head animal performance similar to CG, but with higher herbage mass, ground cover and a desirable pasture composition.

Variation and Correlations among European and North American Orchardgrass Germplasm for Herbage Yield and Nutritive Value

Efforts to improve water-soluble carbohydrate (WSC) concentrations are common in perennial forage grass breeding. Perennial ryegrass (Lolium perenne) breeding has been very successful in developing new cultivars with high WSC and high agronomic performance. Breeding efforts are ongoing to improve the WSC of other perennial forage grasses, such as orchardgrass (Dactylis glomerata). The United States Department of Agriculture Forage and Range and Deutsche Saatveredelung orchardgrass breeding programs cooperated to characterize the expression and genotype by environment interaction (GEI) of water-soluble carbohydrates in a collection of orchardgrass populations from both breeding programs. Additionally, the effort characterized the relationship between water-soluble carbohydrates and other agronomic and nutritive value traits in these populations. Overall, the Deutsche Saatveredelung populations had higher herbage mass (15%), rust resistance (59%), and later maturity. The Forage and Range Research populations had higher water-soluble carbohydrates (4%), nutritive value, and earlier maturity. However, results were highly dependent on GEI. Differences were very pronounced at the French and German field locations, but less pronounced at the two US locations. Combining the germplasm from the Forage and Range Research and Deutsche Saatveredelung programs may be a way to develop an improved base germplasm source that could then be used separately in the EU and US for water-soluble carbohydrate and other trait improvement.

Napier grass (Pennisetum purpureum Schumach) as raw material for bioethanol production: Pretreatment, saccharification, and fermentation

Recently Napier grass (Pennisetum purpureum Schumach) has been recognized to meet the requirement of lignocellulosic bioethanol production, because it has low lignin-content and a relatively high herbage mass per year and per area. Therefore, pretreatment, saccharification, and fermentation processes for ethanol production from Napier grass have been extensively studied. As pretreatment method, acid, alkali, PBHW (pressurized batch hot water), and LMAA (low-moisture anhydrous ammonia) pretreatments were reviewed. As saccharification and fermentation process, saccharification followed by co-fermentation of hexose and pentose, simultaneous saccharification and fermentation (SSF) followed by pentose fermentation, simultaneous saccharification and co-fermentation (SSCF) process were proposed. The SSCF was most advantageous process since the SSCF can prevent contamination risks of other microorganism and can construct simple processing procedure. An example of ethanol production from Napier grass was a combination process of LMAA-pretreatment with SSCF which was performed for of LMAA-treated Napier grass at 36℃ for 96 h using cellulase, xylanase, Saccharomyces cerevisiae, and Escherichia coli KO11. The ethanol yield reached 74.1%. Thus, Napier grass was thought to be a promising biomass for ethanol production.

Preference and behavior of lactating dairy cows given free access to pasture at two herbage masses and two distances.

A number of factors influence dairy cow preference to be indoors or at pasture. The study reported here investigated whether herbage mass and distance affects preference and if continuously housed cows exhibited behavioral and production differences compared to cows that had free access to pasture. Dairy cows (n = 16) were offered a free choice of being in cubicle housing (1.5 cubicles/cow) or at pasture with a high (3,000 ± 200 kg DM/ha) vs. low (1,800 ± 200 kg DM/ha) herbage mass. A control group (n = 16) was confined to cubicle housing for the duration of the study. Each herbage mass was offered at either a near (38 m) or far (254 m) distance in a 2 × 2 factorial crossover design to determine motivation to access pasture. Overall, dairy cows expressed a partial preference to be at pasture, spending 68.7% of their time at pasture. This was not affected (P > 0.05) by herbage mass. Both grass intake (P = 0.001) and grazing time (P = 0.039) was greater when cows were offered the high herbage mass. Neither total mixed ration intake (P > 0.05) nor milk yield (P > 0.05) was affected by herbage mass or distance. Additionally, no interaction existed between herbage mass and distance (P > 0.05). Distance affected preference: overall time on pasture was greater at the near distance (P = 0.002); however, nighttime use was not affected by distance (P = 0.184). Housed cows produced less milk than free-choice cows and this was potentially due to a combination of decreased lying time in housed cows (P < 0.001) and grass intake (1.22 kg/d) in free-choice cows. This study shows that herbage mass is not a major factor driving dairy cow preference for pasture, but distance does affect preference for pasture during the day. Additionally, there are clear production and welfare benefits for providing cows with a choice to be at pasture or cubicle housing over being continuously housed. Further research is necessary to quantify the effect of lying time on milk yields.

Fatty acid intake and rumen fatty acid composition is affected by pre-grazing herbage mass and daily herbage allowance in Holstein dairy cows

The objective of this study was to investigate the effect of level of pre-grazing herbage mass (HM) and daily herbage allowance (DHA) on the fatty acid (FA) intake and composition of ruminal content of grazing dairy cows. Four rumen fistulated Holstein-Friesian dairy cows were allocated to either a high or low HM (1700 vs 2600 kg DM ha-1) and within herbage mass treatment further allocated to a high or low DHA (20 vs 16 kg of DM cow-1 day-1) in a 4 × 4 Latin square design. Total FA intake and linolenic acid (LNA) intake was higher for cows on high DHA (p&lt;0.05). Ruminal oleic acid, linoleic and LNA were not affected by treatments. Ruminal stearic acid (C18:0) and vaccenic acid (VA) concentrations were higher at low HM (43.6 and 14.8 g/100 gof FA respectively; p&lt;0.01) compared to high HM (42.0 and 12.5 g/100 gof FA respectively for C18:0 and VA). Cows grazing high DHA had higher ruminal concentration of VA (15.3 g/100 gof FA; p&lt;0.01) than low DHA (12.1 g/100 gof FA). Regarding milk FA composition, only some of the milk FA varied across treatments, being the VA and LNA concentrations higher at low HM (p&lt;0.05). These data suggest that low HM and high DHA, at least within the range studied here, promotes the accumulation of ruminal VA which could be available for subsequent conversion within the mammary gland to the human health promoting c9,t11 isomer of conjugated linoleic acid.

Effect of pre-grazing herbage mass on dairy cow performance, grass dry matter production and output from perennial ryegrass (Lolium perenne L.) pastures

A grazing study was undertaken to examine the effect of maintaining three levels of pre-grazing herbage mass (HM) on dairy cow performance, grass dry matter (DM) production and output from perennial ryegrass (Lolium perenne L.) pastures. Cows were randomly assigned to one of three pre-grazing HM treatments: 1150 – Low HM (L), 1400 – Medium HM (M) or 2000 kg DM/ha – High HM (H). Herbage accumulation under grazing was lowest (P<0.01) on the L treatment and cows grazing the L pastures required more grass silage supplementation during the grazing season (+73 kg DM/cow) to overcome pasture deficits due to lower pasture growth rates (P<0.05). Treatment did not affect daily milk production or pasture intake, although cows grazing the L pastures had to graze a greater daily area (P<0.01) and increase grazing time (P<0.05) to compensate for a lower pre-grazing HM (P<0.01). The results indicate that, while pre-grazing HM did not influence daily milk yield per cow, adapting the practise of grazing low HM (1150 kg DM/ha) pasture reduces pasture DM production and at a system level may increase the requirement for imported feed.

The effect of pasture pregrazing herbage mass on methane emissions, ruminal fermentation, and average daily gain of grazing beef heifers1

The objective of this study was to determine the effect of pregrazing pasture herbage mass (HM) on CH4 emissions, ruminal fermentation, and ADG of grazing beef heifers at 2 stages of the grazing season. Thirty Limousin cross heifers were allocated to 1 of 2 target pregrazing HM treatments [a low HM (LHM) or high HM (HHM) treatment] for 126 d in a randomized block design experiment. Pasture herbage and heifer rumen fluid samples were collected, and enteric CH4 emissions were determined using an SF6 tracer technique during two 5-d measurement periods [MP; MP 1 (25 to 29 May) and MP 2 (6 to 10 September)]. Both DMI and GE intake (GEI) were measured during MP 2, and ADG of the heifers was measured every 14 d throughout the 126-d grazing period. Mean HM for the LHM and HHM treatments were 1,300 and 2,000 kg DM/ha, respectively, during MP 1 and 2,800 and 3,200 kg DM/ha, respectively, during MP 2. The CP concentration of the offered herbage was greater (P < 0.01) for the LHM treatment during MP 1 and tended (P < 0.1) to be greater for the LHM herbage during MP 2. No difference (P > 0.10) in the NDF concentration of the herbage was found between the HM treatments during MP 1 or 2. There was no effect (P > 0.10) of HM treatment on total CH4 emissions (g/d) for either MP [mean value across HM treatments of 121 (SED 5.4) g/d during MP 1 and 132 (8.8) g/d during MP 2], but CH4 emissions (g) per kilogram of ADG were reduced (P < 0.05) from heifers fed the LHM treatment during MP 1 and 2 [mean values for LHM and HHM of 135 and 163 (SED 9.5) g/kg, respectively, during MP 1 and corresponding values of 150 and 194 (9.9) g/kg during MP 2]. Heifers fed the LHM treatment had greater (P < 0.001) ADG throughout the grazing period [mean value across the 126-d grazing period of 0.88 (SEM 0.032) kg/d] than those fed the HHM treatment [corresponding value of 0.73 (0.034)]. For MP 2, CH4 emissions per kilogram of DMI (g CH4/kg DMI) and per megajoule of GEI (MJ CH4/MJ GEI) tended (P ≤ 0.08) to be less for heifers fed the LHM [19.3 (0.08) g/kg and 0.056 (0.0020) MJ/MJ, respectively] than for the HHM (21.1 g/kg and 0.061 MJ/MJ) treatment, and there were no differences (P > 0.10) in DMI or GEI of the heifers between the HM treatments. The results of this study suggest that offering a low pregrazing HM sward will reduce enteric CH4 emissions relative to ADG throughout the grazing season because of increased ADG.

Does pre‐grazing herbage mass really affect herbage intake and milk production of strip‐grazing dairy cows?

AbstractThe effect of pre‐grazing herbage mass (HM) on herbage intake and milk production of strip‐grazing dairy cows is usually studied at the same herbage allowance (HA). In the literature, the effect of HM seems to be affected by the cutting height above which HA is estimated. The aim of this 2 × 3 factorial study was to determine whether the effect of HM (low vs high HM) on herbage intake, milk production and grazing behaviour of dairy cows is affected by the HA estimation height (ground level vs 2·5 vs 5 cm). Two HMs were compared in three different ways: at same HA above ground level (SHA0), at same HA above 2·5 cm (SHA2) and at same HA above 5 cm (SHA5). During two consecutive years, twenty‐four Holstein‐Friesian dairy cows in mid‐lactation were assigned to one estimation height in an incomplete switchback design, with two 14‐d periods. There was an interaction between HM and estimation height for herbage intake and milk production. The effect of HM on herbage intake was positive, null and negative when HMs were compared at SHA0, SHA2and SHA5, respectively. This study may have practical implications on future research for studying, directly or indirectly, the effect of pre‐grazing HM under strip‐ or rotational‐grazing management, and on modelling herbage intake at grazing.

Tiller demography in tall fescue (Festuca arundinacea) swards as influenced by nitrogen fertilization, sowing method and grazing management

AbstractTall fescue is an important temperate grassland species globally, but in many regions the effects of drought, heat and poor grazing management, reduce its persistence in summer. Furthermore, poor ground cover and low tiller population density (TP) in winter result in low radiation capture and thus limited potential to increase the low growth rates at that time. Knowledge of the effect of fertilization, defoliation managements and establishment methods on demography of tall fescue would help to improve sward management for better persistence and winter growth. Accordingly, an experiment was carried out in Pergamino, Argentina, to study the effects of two N‐ fertilizer levels, two grazing frequencies and two seeding row arrangements upon tall fescue TP demography. Herbage mass, tiller appearance (TA) and death rates were measured over 3 years. Seasonal fluctuations in TA and death rates determined well‐defined periods of increase and decrease in TP density. Maximum values were found at the end of winter and minimum ones at the end of spring, after the reproductive period. Nitrogen shortage and high herbage mass limited TA. Tiller death rate followed TA rate and was affected by nitrogen supply and defoliation frequency in the same way that TA was. Sowing arrangement affected tiller demography at the beginning of the experiment.

The influence of herbage mass and supplementary feeding on nutrient flows and animal performance in grazing, lactating ewes

SUMMARYThe present paper examines the effect of the type of supplement given to grazing ewes in early lactation on the performance of ewes and lambs on temperate sown pastures. Lactating ewes grazed perennial ryegrass pastures at either low- or high-herbage masses, between days 8 and 96 of lactation. On the low-herbage mass treatments, ewes were either unsupplemented or received either an energy supplement (sugarbeet pulp) or a protein supplement (1:1 sugarbeet pulp:formaldehyde-treated soyabean meal) between days 8 and 50 of lactation. The provision of supplements or the higher herbage mass led to increases in live weight (LW) and body condition score of ewes during days 8–50 of lactation, while unsupplemented ewes on the low-herbage mass treatment lost LW and had lower body condition scores. After supplementation finished, previously supplemented ewes or those grazing the higher herbage mass lost LW and condition, while unsupplemented ewes grazing the low-herbage mass gained both LW and condition. Non-treatment factors such as ewe dentition score significantly affected ewe and lamb LW gains. Regression analyses indicated that lamb LW gains between days 8 and 50 of lactation were 40–60 g/d greater in lambs from supplemented ewes or ewes grazing the higher herbage mass cf. unsupplemented ewes. Overall, there was no difference in the response of ewes or lambs to the type of supplement. Milk yields were estimated in a subset of ewes (replicate 4). Ewes on the high-herbage mass treatment or those supplemented with protein had higher milk yields than those on the low-herbage mass treatment or those given the energy supplement. Supplemented ewes in this replicate had higher metabolizable energy intakes (MEIs). Measurements of digesta flow in a further subset of ewes indicated that both supplements resulted in greater ruminal and post-ruminal supplies of energy and protein than in the unsupplemented ewes at the lower herbage mass, but differences in ruminal and post-ruminal nutrient provision between the supplements were less than had been intended. It is suggested that this is the reason for there being no statistical difference in the performance of ewes and lambs in response to the type of supplement.

Stand Maintenance and Genetic Diversity of Bermudagrass Pastures under Different Grazing Management Strategies during a 38‐Year Period

ABSTRACTStocking rate can affect production and persistence of bermudagrass [Cynodon dactylon (L.) Pers.] pastures. ‘Coastal’ and common bermudagrass pastures were grazed at different stocking rates to maintain specific low, medium, and high herbage mass (HM) during a 38‐yr period. From 1969 to 1984, pastures received identical fertilization, and from 1985 to 2005, regimens of N plus annual ryegrass (Lolium multiflorum Lam.) vs. no N plus clover (Trifolium spp.) were superimposed on each bermudagrass × HM. Stand of both Coastal and common bermudagrass was negatively affected by decreasing HM and no N fertilizer. Bahiagrass (Paspalum notatum Flüggé) was the primary non‐bermudagrass invasive species on no‐N pastures. Invasive bermudagrass ecotypes were more abundant at 73 to 86% on low HM Coastal with clover or ryegrass, respectively. On common bermudagrass, ecotypes were present at about 25 and 40%, respectively, on clover and ryegrass but not affected by HM. During October 2005, 125 whole plant‐root core ecotypes were collected and fingerprinted using amplified fragment length polymorphism (AFLP) markers, analyzed via coefficient of genetic similarity matrix, and clustered in genetically related groups. Four groups were identified in Coastal and five in common bermudagrass. The Coastal and Coastal‐similar ecotypes were different from common bermudagrass and common bermudagrass‐similar ecotypes in plant height, leaf length, leaf width, and leaf coarseness. Plant inflorescence characteristics of ecotype ranked similar to those of growth traits. The bermudagrass were most sustainable under moderate to high HM and with N fertilization.

Fine‐scale spatial distribution of herbage mass, herbage consumption and fecal deposition by cattle in a pasture under intensive rotational grazing

AbstractHerbage mass, herbage consumption and fecal deposition by animals were monitored for 2 years in 182 fixed locations (0.5 × 0.5 or 1 × 1 m) in a sown pasture (1.1 ha) grazed rotationally by cattle (42–45 animals). Fecal deposition was more spatially variable (higher values of coefficient of variation) than herbage mass and consumption, with consistently significant bias from the normal distribution in both skewness and kurtosis. In terms of spatial pattern, herbage mass and consumption were always or almost always spatially heterogeneous (nonrandom spatial pattern), while fecal deposition was less frequently heterogeneous or usually homogeneous (random spatial pattern). The spatial heterogeneity in herbage mass was interpreted as being created in the early grazing season possibly through spatial heterogeneity in soil‐related factors, and maintained until the late grazing season mainly by herbivory where the animals always left more herbage uneaten at locations with higher pre‐grazing herbage mass. Even when cumulated for 2 years (56 days of grazing), herbage consumption and fecal deposition were still considerably spatially variable. Such nonuniform cumulation of animal impacts, however, is not likely to have a negative effect on the grazing system (paddock as the major grazing area) because (1) the animals almost always consumed more herbage from locations with higher herbage mass, resulting in a less variable degree of utilization (consumption/production) across the paddock; (2) fecal deposition on the paddock was not abundant, due to the concentration of feces in the resting area adjoined; and (3) fertilizer was regularly applied to the paddock as management.