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1.
A winter grazing experiment was conducted to evaluate the effects of stocking rate and corn gluten feed supplementation on forage mass and composition and the BW and BCS of bred 2-yr-old cows grazing stockpiled forage during winter. Two 12.2-ha blocks containing Fawn, endophyte-free, tall fescue and red clover were each divided into 4 pastures of 2.53 or 3.54 ha. Hay was harvested from the pastures in June and August of 2003 and 2004, and N was applied at 50.5 kg/ha at the initiation of stockpiling in August. On October 22, 2003, and October 20, 2004, twenty-four 30-mo-old Angus-Simmental and Angus cows were allotted by BW and BCS to strip-graze for 147 d at 0.84 or 1.19 cow/ha. Eight similar cows were allotted to 2 dry lots and fed tall fescue-red clover hay ad libitum. Corn gluten feed was fed to cows in 2 pastures to maintain a mean BCS of 5 (9-point scale) at each stocking rate and in the dry lots (high supplementation level) or when weather prevented grazing (low supplementation level) in the remaining 2 pastures at each stocking rate. Mean concentrations of CP in yr 1 and 2 and IVDMD in yr 2 were greater (P < 0.10) in hay than stockpiled forage over the winter. At the end of grazing, cows fed hay in dry lots had greater (P < 0.05) BCS in yr 1 and greater (P < 0.10) BW in yr 2 than grazing cows. Grazing cows in the high supplementation treatment had greater (P < 0.10) BW than cows grazing at the low supplementation level in yr 1. Cows in the dry lots were fed 2,565 and 2,158 kg of hay DM/cow. Amounts of corn gluten feed supplemented to cows in yr 1 and 2 were 46 and 60 kg/ cow and did not differ (P = 0.33, yr 1; P = 0.50, yr 2) between cows fed hay or grazing stockpiled forage in either year. Estimated production costs were greater for cows in the dry lots because of hay feeding.  相似文献   

2.
Performance and production of growing cattle (Bos taurus) on Coastal Bermudagrass [Cynodon dactylon (L.) Pers.] pasture are affected by forage allowance, but possible interactions with fertilizer nutrient source (i.e., inorganic vs. organic) and time have not been well described. We evaluated the effects of 3 nutrient sources with equivalent N rates: 1) inorganic, 2) crimson clover (Trifolium incarnatum L.) cover crop plus inorganic, and 3) chicken (Gallus gallus) broiler litter, factorially arranged with 2 residual forage mass levels [grazing to maintain high (4,528 +/- 1,803 kg/ha) and low (2,538 +/- 1,264 kg/ha) forage mass], on cattle stocking density, ADG, and BW gain during 5 consecutive summer grazing seasons. Across grazing seasons, residual forage mass and nutrient source both affected response variables, but interactions between these variables were rarely significant (P < or = 0.10). Across grazing seasons and nutrient sources, increasing grazing pressure to maintain a lower forage mass reduced ADG (0.67 vs. 0.88 kg/d; P < 0.001) but increased BW gain/ha (726 vs. 578 kg/ha; P < 0.001) due to greater stocking density (8.7 vs. 5.8 steers/ha, P < 0.001; mean BW of growing Angus steers of 212 kg). Inorganic fertilization led to greater stocking density than other nutrient sources (8.2 vs. 6.8 steers/ha, P < 0.001) because of greater forage production. Stocking density to achieve the 2 targeted forage mass levels was widely different during the initial grazing seasons of the study but nearly similar at the end of 5 yr. Cattle performance tended to decline with time during each grazing season under both residual forage mass levels, perhaps as a result of declining forage quality, because performance was positively associated with grazing season precipitation under high forage mass. Steer BW gain/ha was greater (P < 0.05) with lower forage mass early in the grazing season of all years but not necessarily later in the grazing season. Steer BW gain/ha was also greater (P < 0.05) with a lower forage mass during the early years of the study but was similar during the later years of the study. Significant variations in cattle performance and production with time confirmed the short-term seasonal effects but suggested that the long-term effects may also be of importance in maintaining productivity and environmental quality of grazed pastures.  相似文献   

3.
Sixty-four spring-calved primiparous crossbred cows paired by calving date and body condition score (BCS) at calving were used to study the effect of a short-term increase in the nutritional plane before the mating period on cow and calf performance, changes in metabolic and endocrine parameters and hepatic gene expression. At 48 ± 10 days post-partum (onset of nutritional treatment = day 0), cows were assigned to two treatments during 23 days: control (grazing of native pastures; NP; n = 31) and increased nutritional plane (NP improved with Lotus subbiflorous cv Rincon; IP; n = 33). Cow body weight (BW), BCS and total protein and albumin concentrations increased while urea and non-esterified fatty acids levels decreased from the beginning of the nutritional treatment in both groups, indicating the animal positive energy balance as forage growth and availability of pastures increased during spring. In addition, cow BW and BCS, as well as calf average daily gain and BW, were greater in IP than in NP cows groups. Insulin concentrations were less in IP than in NP (1.37 vs. 2.25 ± 0.26 μU/ml) because insulin increased owing to nutritional treatment only in NP cows. Hepatic insulin receptor mRNA at day 23 tended to be 1.5-fold greater, while insulin growth factor binding protein-3 mRNA expression was 1.7-fold greater in NP than in IP cows. Reproductive responses were not affected by nutritional treatment, but days to initiation of ovarian ciclicity (108 ± 10 days) were positively correlated with insulin concentrations. Grazing of improved NP for 23 days before the mating period did not improve cow reproductive performance but modified metabolic, endocrine and gene expression parameters, in agreement with greater nutrient and energy partitioning towards milk production, reflected in better calf performance.  相似文献   

4.
本试验为研究冷季营养匮乏对放牧牦牛和黄牛血清生化指标、瘤胃发酵参数及放牧行为的影响,选取体重相近、健康无病的4岁母牦牛和母黄牛各10头,分别于2018年11月、2019年1和3月佩戴MOOnitor监测系统对其放牧行为进行研究.在试验期末(2019年3月)采集牧草样品、瘤胃液和血液,用于牧草营养成分、血清生化指标和瘤胃...  相似文献   

5.
基于藏北高原的3个围栏与自由放牧试验样地,探讨了高寒草地牧草营养品质对放牧的响应机制。结果表明：在一个高寒草原化草甸冷季牧场,冷季放牧分别减少了24.29%和18.98%的杂草酸性洗涤纤维和中性洗涤纤维含量,并增加了41.05%的杂草粗灰分含量,从而增加了杂草营养品质;而没有改变群落和优势牧草营养品质。在一个高寒草原化草甸暖季牧场,暖季放牧分别减少了31.82%和27.45%的群落酸性洗涤纤维和中性洗涤纤维含量,并分别增加了137.35%和24.73%的群落粗灰分和粗脂肪含量,从而增加了群落营养品质;暖季放牧分别减少了22.04%和22.50%的优势牧草酸性洗涤纤维和中性洗涤纤维含量,并增加了202.19%的优势牧草粗灰分含量,从而增加了优势牧草营养品质;而没有改变杂草营养品质。在一个高寒草甸暖季牧场,暖季放牧分别减少了37.18%和25.10%的杂草酸性洗涤纤维和中性洗涤纤维含量,从而增加了杂草营养品质;增加了26.55%的优势牧草粗蛋白含量,从而趋于增加了优势牧草营养品质;而对群落营养品质无影响。植物群落营养品质与植物群落α和β多样性相关,优势牧草营养品质主要与土壤变量相关,杂草营养品质与土壤变量和杂草α多样性有关。因此,藏北高寒草地牧草营养品质对放牧的响应因草地类型和放牧季节的不同而不同,高寒草地应该采取分类放牧管理。  相似文献   

6.
青海省海晏县牧场牧草营养品质全年动态   总被引：2，自引：0，他引：2  
为弥补众多青藏高原定点监测全年牧草营养价值变化对生产支撑不足的问题,探明青藏高原放牧牦牛全年轮牧条件下牧草的全年动态营养价值,本研究选取青藏高原典型牧户的放牧草地,于2015年9月到2016年8月全年跟踪放牧牦牛、模拟采集可食性牧草,并分析牧草常规营养成分及总能,采用体外两阶段法测定牧草体外干物质消化率。结果表明,1)牧草中粗蛋白(CP)、粗脂肪(EE)、酸性洗涤纤维(ADF)、中性洗涤纤维(NDF)、粗灰分(Ash)、钙(Ca)和磷(P)含量分别为3.68%~19.21%、0.86%~2.74%、9.65%~43.83%、44.70%~76.23%、5.40%~9.62%、2.13%~5.12%和0.027%~0.190%,5月份CP、Ash含量极显著高于其他月份(P0.01);2)体外两阶段法评定牧草体外干物质消化率得出,消化率为42.72%~72.47%,5月份极显著高于其他月份(P0.01);3)牧草总能(GE)、消化能(DE)和代谢能(ME)分别为17.76~19.67、7.81~13.26和6.40~10.87 MJ·kg~(-1),全年不同月份牧草GE差异不显著(P0.05),以6月份最高,11月份次之,牧草DE及ME为5月份显著高于其他月份(P0.05),4月份和6月份次之,12月份最低。青海省海晏县牧场5月和6月天然牧草品质优良,10月至翌年3月牧草营养价值较低。因此,建议牧民和养殖户在10月到翌年3月采用天然草地配合补饲饲料养殖;鉴于全年轮牧季节性草地类型不同,今后应采取跟踪式牧草营养监测方法,较好地实现放牧牦牛精准补饲。  相似文献   

7.
We examined the effect of endophyte infection level of tall fescue (Festuca arundinacea Schreb.) used for stockpiled forage on the performance of lactating, fallscalving beef cows and their calves. Treatments were endophyte infection levels of 20% (low; SEM = 3.5), 51%, (medium; SEM = 1.25), and 89% (high; SEM = 2.4; 4 replications/treatment). Five cow-calf pairs grazed in each replicate (n = 60 cow-calf pairs/yr) for 84 d (phase 1) starting on December 2, 2004 (yr 1), and December 1, 2005 (yr 2). After 84 d of grazing each treatment, the cattle were commingled and fed as a single group (phase 2) until weaning in April of each year. Phase 2 allowed measurement of residual effects from grazing stockpiled tall fescue with varying levels of endophyte infection. Pregrazing and postgrazing forage DM yield, forage nutritive value, and total ergot alkaloid concentrations of forage were collected every 21 d during phase 1. Animal performance data included cow BW, ADG, and BCS, as well as calf BW and ADG. Animal performance was monitored during both phases. Endophyte infection did not affect (P = 0.52) apparent intake (pregrazing minus postgrazing forage DM yield) of stockpiled tall fescue, because each cow-calf pair consumed 16 +/- 1.7 kg/d regardless of treatment. Cow ADG during phase 1 was -0.47 +/-0.43 kg for the low treatment, which was greater (P < 0.01) than either the medium (-0.64 +/-0.43 kg) or high (-0.74 +/- 0.43 kg) treatments. However, cows that had grazed the high or medium treatments in phase 1 lost -0.43 and -0.57 (+/-0.24) kg/d, respectively, which was less (P < 0.01) BW loss than the cows in the low (-0.78 +/- 0.24 kg/d) treatment during phase 2. By the end of phase 2, cow BW did not differ (528 +/-27 kg; P = 0.15). Body condition score for cows in the low treatment was greater (P = 0.02) than that of the medium and high treatments at the end of phase 1. Body condition scores did not change appreciably by the end of phase 2, and differences among treatments remained the same as at the end of phase 1 (P = 0.02). In contrast to cow performance, calf ADG was unaffected (P = 0.10) by endophyte level and averaged 0.73 +/- 0.07 kg during phase 1 and 0.44 +/- 0.04 kg during phase 2. Our data suggest that fall-calving herds can utilize highly-infected tall fescue when stockpiled for winter grazing, with little impact on cow performance and no impact on calf gain.  相似文献   

8.
Cow and calf performance was determined in a 2-yr, 2 x 2 factorial, grazing experiment using Coastal or Tifton 85 (T85) replicated Bermudagrass pastures (4 pastures each; each pasture 4.86 ha), without or with aeschynomene creep-grazing paddocks (n = 4, 0.202 ha each, planted in May of each year, 13.44 kg/ha). On June 10, 2004, and June 8, 2005, 96 winter-calving beef "tester" cows and their calves were grouped by cow breed (9 Angus and 3 Polled Hereford/group), initial cow BW (592.9 +/- 70.1 kg, 2-yr mean), age of dam, calf breed (Angus, Polled Hereford, or Angus x Polled Hereford), calf sex, initial calf age (117 +/- 20.1 d, 2-yr mean), and initial calf BW (161.3 +/- 30.4 kg) and were randomly assigned to pastures. Additional cow-calf pairs and open cows were added as the forage increased during the season. Forage mass was similar for all treatment pastures (P > 0.70; 2-yr mean, 6,939 vs. 6,628 kg/ha, Coastal vs. T85; 6,664 vs. 6,896 kg/ha, no creep grazing vs. creep grazing). Main effect interactions did not occur for performance variables (P > 0.10; 2-yr means), and year affected only the initial and final BW of the calves and cows. The 91-d tester calf ADG was greater for calves grazing T85 than Coastal (0.94 vs. 0.79 kg; P < 0.01), and for calves creep grazing aeschynomene compared with calves without creep grazing (0.90 vs. 0.82 kg; P < 0.03). Calf 205-d adjusted weaning weights were increased for calves grazing T85 compared with Coastal (252.9 vs. 240.3 kg; P < 0.01) and for calves with access to creep grazing (249.9 vs. 243.3 kg; P < 0.05). The IVDMD of esophageal masticate from pastures had a forage x creep grazing interaction (P < 0.05; Coastal, no creep grazing = 57.4%; Coastal, creep grazing = 52.1%; T85, no creep grazing = 59.1%; T85, creep grazing = 60.0%), and IVDMD was greater (P < 0.05) for T85 than for Coastal pastures. Cows were milked in August 2004, and in June and August 2005, with variable milk yields on treatments, but increased milk protein (P < 0.05) for cows grazing T85 compared with Coastal pastures in August each year, contributing to increased calf gains on T85 pastures. These results complement previous research with T85 and indicate increased forage quality and performance of cattle grazing T85 pastures. Calf gains on T85 pastures and for calves on creep-grazed aeschynomene paddocks were high enough to influence the efficiency of cow-calf operations.  相似文献   

9.
A bioeconomic computer model was used to evaluate alternate calving seasons in a cow-calf enterprise under range conditions representative of the Northern Great Plains. The simulated ranch utilized a rotational breeding system based on Hereford and Angus and had a fixed forage base (4,500 animal unit months of native range, 520 t of grass hay, and 183 t of alfalfa hay). Calving seasons studied were spring (SP, beginning March 15), summer (SU, beginning May 15), and fall (FA, beginning August 15). Weaning dates were October 31, December 15, and February 1, for SP, SU, and FA. The SP system was also simulated with a 5% increase in calf mortality (SP-IM), and SU with early weaning on October 31 (SU-EW). Herd size for the fixed resource was 509, 523, 519, 560, and 609 cows exposed per year for SP, SP-IM, SU, SU-EW, and FA, respectively. Corresponding values for weight weaned per cow exposed were 206, 186, 193, 153, and 145 kg. Steer calves, nonreplacement heifer calves, and cull cows were sold at the time of weaning. Quarterly cattle and feed prices used were representative of the peak, descending, valley, and ascending phases of the 1990s cattle cycle adjusted for inflation. Estimates of ranch gross margin (gross returns minus variable costs) were greatest for SP, followed by SP-IM, SU, SU-EW, and FA, and the ranks were consistent across phases of the cattle cycle. Differences between ranch gross margin for SP-IM and SU were small. In beef enterprises representative of the Northern Great Plains, with a restricted grazing season, limited access to low-cost, high-quality grazeable forage, and with calves sold at weaning, switching from early spring to a summer or fall calving date is not expected to improve profitability. If delaying calving improves calf survival, then calving in early summer may be a competitive choice.  相似文献   

10.
Indigenous rangeland management practices, forage quality and availability, and livestock production by pastoralists and agro-pastoralists in miombo woodlands were investigated in a study conducted in Kilosa district, Tanzania. The study methods comprised household interviews, key informant and focus group discussions, and forage laboratory analyses. Preferred forage species and indigenous rangeland and livestock management practices among pastoral and agro-pastoral communities in miombo woodlands were identified, and the nutrient content of the forages was determined. In general, rangeland management in the study area faces challenges such as unclear or disputed land tenure regime and lack of technical knowledge. Moreover, the nutritional value of some native forage species identified in miombo was found to be too low to meet the nutrient requirements of livestock. Livestock in miombo contribute greatly to household livelihoods and food security, but forage scarcity was identified as a limiting factor. Overall, it was concluded that rangeland improvement practices are poor or nonexistent in allocated grazing areas in Kilosa’s miombo woodlands.  相似文献   

11.
Our objective was to evaluate a replicated (n = 2) Midwestern year-round grazing system's hay needs and animal production compared with a replicated (n = 2) conventional (minimal land) system over 3 yr. Because extended grazing systems have decreased hay needs for the beef herd, it was hypothesized that this year-round system would decrease hay needs without penalizing animal production. In the minimal land (ML) system, two replicated 8.1-ha smooth bromegrass-orchardgrass-birdsfoot trefoil (SB-OG-BFT) pastures were rotationally stocked with six mature April-calving cows and calves and harvested as hay for winter feeding in a drylot. After weaning, calves were finished on a high-concentrate diet. Six mature April-calving cows, six mature August-calving cows, and their calves were used in the year-round (YR) grazing system. During the early and late summer, cattle grazed two replicated 8.1-ha SB-OG-BFT pastures by rotational stocking. In mid-summer and winter, April- and August-calving cows grazed two replicated 6.1-ha, endophyte-free tall fescue-red clover (TF-RC) and smooth bromegrass-red clover (SB-RC) pastures, respectively, by strip-stocking. In late autumn, spring-calving cows grazed 6.1-ha corn crop residue fields by strip-stocking. Calves were fed hay with corn gluten feed or corn grain over winter and used as stocker cattle to graze SB-OG-BFT pastures with cows until early August the following summer. First-harvest forage from the TF-RC and SB-RC pastures was harvested as hay. Body condition scores of April-calving cows did not differ between grazing systems, but were lower (P < or = 0.03) than those of August-calving cows from mid-gestation through breeding. Preweaning calf BW gains were 47 kg/ha of perennial pasture (P < 0.01) and 32 kg/cow (P = 0.01) lower in the YR grazing system than in the ML system. Total BW gains ofpreweaning calf and grazing stocker cattle were 12 kg/ha of perennial pasture less (P = 0.07), but 27 kg/cow greater (P = 0.02) in pastures in the YR grazing system than in the ML system. Amounts of hay fed to cows in the ML system were 1,701 kg DM/cow and 896 kg DM/cow-stocker pair greater (P < 0.05) than in the YR grazing system. Extended grazing systems in the Midwest that include grazing of stocker cattle to utilize excess forage growth will decrease stored feed needs, while maintaining growing animal production per cow in April- and August-calving herds.  相似文献   

12.
A study was conducted on foothills rangeland to determine whether grazing patterns differed among cow breeds and to determine whether there was a relationship between individual grazing patterns and performance of beef cows. Hereford (HH), Tarentaise (TT), 3/4 Hereford x 1/4 Tarentaise (3H1T), 1/2 Hereford x 1/2 Tarentaise (HT), and 1/4 Hereford x 3/4 Tarentaise (1H3T) cows were observed during the summers of 1997 (n = 183) and 1998 (n = 159). Locations of individual cows were recorded two to three times per week during 1.5- to 2.5-h periods in the morning by observers on horseback. Statistical models included cow breed, age, and nursing status. Data from each year were analyzed separately. During 1997 and 1998, nonlactating cows were located at greater (P < 0.05) vertical distances from water than lactating cows. In 1998, nonlactating cows used steeper (P < 0.05) slopes than lactating cows. However, nonlactating cows did not travel as far horizontally from water (P < 0.05) as lactating cows in 1997. Younger cows (3 yr) traveled further (P < 0.05) from water both vertically and horizontally than older cows (5+ yr) in 1997, but not during 1998. Tarentaise and 1H3T cows were observed at greater (P < 0.05) vertical distances from water than HH cows during both years of the study. During 1998, TT and 1H3T cows used steeper (P < 0.05) slopes than HH cows. Using residual correlations, there were no consistent relationships between topographic aspects of individual grazing locations and cow weight, height, and body condition score. In 1997, cows with earlier calving dates and correspondingly heavier calf weaning weights used areas that had greater vertical distances to water; however, in 1998 there were no relationships (P > 0.05) of calving date and weaning weight with cow location. During both years, pregnant and nonpregnant cows used terrain similarly (P > 0.05), which suggests that cow reproductive performance was not related to terrain use. Grazing patterns in foothills rangeland varied among cow breeds. Performance of cows that used more rugged topography was similar to cows using gentler terrain.  相似文献   

13.
Two studies were conducted to evaluate the effectiveness of low-moisture blocks (LMB) and conventional dry mixes (CDM) for supplementing minerals to cattle on rangeland and to modify grazing patterns. In study 1, cows were fed LMB or CDM on moderate or difficult foothill terrain in Montana during autumn and winter. Cows consumed more CDM in moderate terrain than difficult terrain, but intake of LMB was similar in both terrain types. Using global positioning system (GPS) telemetry data, visits to supplements were defined as collared cow positions within 10 m of placement sites. More cows visited LMB (74%) than CDM (56%). More cows visited supplements (LMB and CDM pooled) when placed in moderate rather than difficult terrain. Cows spent more nonresting time within 100 and 200 m of LMB than CDM. In study 2, CDM and LMB designed to supplement minerals (LMB-M) were compared when cows were also fed LMB designed to supplement protein (LMB-P). Comparisons were made with cows grazing rangeland and with cows fed hay. Intake of LMB-P and CDM was less when cows grazed rangeland than when they were fed hay. Cows consumed less LMB-P when LMB-M was available. More cows visited LMB-M than CDM, and cows visited LMB-M more frequently than CDM. The LMB formulations designed to supplement minerals work well with formulations designed to supplement protein. Both LMB and CDM met estimated deficits of minerals in the forage based on supplement intake (g·day-1) and forage evaluations, but cows visited LMB more consistently than CDM. Low-moisture blocks appear to be more attractive to cows than CDM and should be more useful to modify grazing patterns on rangeland.  相似文献   

14.
To establish the effect of sward height, concentrate feeding time, and restricted time for grazing on forage utilization by grazing cattle, 32 crossbred beef (24 Angus and eight Hereford) cows (632 kg BW) and calves (104 kg BW) were grouped by weight and calving date. They were assigned randomly to two sward height treatments (4 to 8 or 8 to 12 cm), replicated four times. The herbage comprised mainly Kentucky bluegrass, orchardgrass, some forbs, and white clover. The cows were restricted to 12 h/d grazing (0700 to 1900) or unrestricted to 24 h/d grazing and fed a concentrate supplement (4.1 kg DM.cow(-1).d(-1), approximately 0.65% of BW or 33% of total DMI) either at 0700 or 1800. The experiment was repeated over three 15-d periods in May, June/July, and August 2000. The herbage on high sward height pasture was higher (P = 0.06) in NDF and ADF and lower (P < 0.01) in CP than low sward height herbage. For cows restricted to 12 h/d grazing, supplementing at 0700 as opposed 1800 resulted in greater (P = 0.04) forage DMI (8.6 vs. 8.1 kg/d), whereas cows that were unrestricted showed little change (8.2 kg/d at 0700 vs. 8.4 kg/d at 1800). Supplementing at 1800 as opposed to 0700 resulted in greater (P = 0.03) herbage DM digestibility (67.7 vs. 64.5%) for cows on high sward height, whereas cows on low sward height exhibited minimal differences (65.4% at 1800 vs. 66.3% at 0700). Cows restricted to 12 h/d grazing and supplemented at 0700 as opposed to 1800 resulted in greater (P = 0.06) digestible DMI (5.0 vs. 4.7 kg/d), whereas unrestricted cows exhibited the opposite response (4.6 kg/d digestible DMI at 0700 vs. 4.9 kg/d at 1800). Supplementing at 1800 as opposed to 0700 increased the time spent grazing to a greater (P = 0.09) extent for restricted than for unrestricted cows. When forage availability or grazing time was limiting (due to a low forage allowance and restricted access to forage, respectively) supplementing concentrates at 0700 resulted in greater forage utilization and intake rate because of increased forage DMI, DM digestibility, and digestible DMI. However, when forage or grazing time was not limiting, supplementing concentrates at 1800 resulted in greater forage utilization because of increased forage DM digestibility.  相似文献   

15.
本试验旨在探明青海省主要牦牛饲养区海晏县牦牛的营养状况,为制定添补措施提供科学依据。于2015-09—2016-08跟踪测定了青海省海晏县牧户草场天然牧草产量以及牦牛干物质采食量、体重和血清生化指标,同时分析平均日增重与血清生化指标的相关性。结果表明:天然牧草可食草产量7月份高于其他月份;春季牦牛干物质采食量显著高于秋、冬季(P0.05),秋季显著低于其他季节(P0.05);1月份、2月份、3月份、10月份、11月份、12月份牦牛平均日增重呈现负增长,4月份后逐渐上升,6月份、7月份显著高于其他月份(P0.05);血清葡萄糖(GLU)的含量7月份显著高于除6月份、10月份外的其他月份(P0.05);2月份、3月份血清尿素氮(UN)含量及碱性磷酸酶(ALP)活性低于其他月份;由相关性分析可知,平均日增重与血清UN含量呈显著的正相关(P0.05)。综合得出,青海省海晏县10月份至次年3月份为饲草供给不足,牦牛平均日增重呈现负增长,4月份后平均日增重逐渐上升,因此,建议轮牧的放牧形式下,10月份至次年3月份,采用天然草场配合补饲饲料的饲养方式。  相似文献   

16.
In order to optimize the production of embryos under tropical conditions and to test a possible seasonal effect on embryo quality, 40 Zebu cows were superovulated during the dry season (April to May) and during the rainy season (July to August). A total of 116 (average 2.7/cow) and 83 embryos (3.5 average/cow) were obtained during the respective seasons. After classification as good, fair or poor quality, embryos were tested based on their ultrastructural differences (n = 53 dry season 16 good, 20 fair and 17 poor and n = 61 rainy season 21 good, 20 fair and 20 poor) and their degree of apoptosis using the TUNEL technique (n = 30 during the dry season and n = 55 in the rainy season). Structural characteristics determining embryo quality varied between good and fair quality embryos. No difference, however, was observed between good, fair and poor quality embryos from the two seasons. The number of TUNEL-positive cells was different among embryos (p < 0.001), being lower in labelled cells of good quality embryos regardless of the season. Fewer apoptotic cells were observed in embryos assigned in all three quality levels during the rainy season (p < 0.001). Ultrastructural evaluations confirmed the results obtained by TUNEL. Cryopreserved embryos of good (n = 25 in each season) and fair quality (n = 11 dry season; n = 17 rainy season) showed a significant decrease of TUNEL-positive cells during the rainy season (p < 0.05). Results suggest that embryos collected in the dry season have more cellular damage in contrast; embryos cryopreserved in the rainy season appeared morphologically better equipped to result in a pregnancy following transfer.  相似文献   

17.
A 2-yr grazing experiment was conducted to assess the effects of grazing management on cattle distribution and pasture and stream bank characteristics. Six 12.1-ha cool-season grass pastures in central Iowa were allotted to 1 of 3 treatments: continuous stocking with unrestricted stream access (CSU), continuous stocking with stream access restricted to 4.9-m-wide stabilized crossings (CSR), or rotational stocking with stream access restricted to a riparian paddock (RP). Pastures were stocked with 15 fall-calving Angus cows (Bos taurus L.) from mid-May to mid-October for 153 d in 2008 and 2009. A global positioning system (GPS) collar recording cow position every 10 min was placed on at least 1 cow per pasture for 2 wk of each month from May through September. Off-stream water was provided to cattle in CSU and CSR treatments during the second of the 2 wk when GPS collars were on the cattle. A black globe temperature relative humidity index (BGTHI) was measured at 10-min intervals to match the time of the GPS measurements. Each month of the grazing season, forage characteristics (sward height, forage mass, and CP, IVDMD, and P concentrations) and bare and fecal-covered ground were measured. Stream bank erosion susceptibility was visually scored in May, August, and October (pre-, mid-, and post-stocking). Cattle in RP and CSR treatments spent less time (P < 0.10) within the stream zone (0 to 3 m from stream center) in June and August and in the streamside zone (0 to 33 m from stream zone) in May through August and May through September, respectively, than cattle in CSU pastures. However, off-stream water had no effect on cattle distribution. Compared with the CSU treatment, the CSR treatment reduced the probability (P < 0.10) that cattle were within the riparian zone (0 to 36 m from stream center) at BGTHI of 50 to 100. Bare ground was greater (P < 0.10) in pastures with the CSU than CSR and RP treatments in the stream and streamside zones in September and October and in July and September. Streams in pastures with the CSU treatment had less stable banks (P < 0.10) mid- and post-stocking than RP or CSR treatments. Results show that time spent by cattle near pasture streams can be reduced by RP or CSR treatments, thereby decreasing risks of sediment and nutrient loading of pasture streams even during periods of increased BGTHI.  相似文献   

18.
Thirty-two mature, pregnant beef cows (avg age 8 yr, body wt 550 kg) grazing oat pastures were used to determine the effects of lasalocid on serum mineral and ruminal fluid volatile fatty acid (VFA) concentrations. Cows were blocked by breed type and assigned randomly to eight, 2-ha pastures containing oat forage from December 17, 1985 to May 6, 1986. The cows were fed .25 kg of ground corn with or without 200 mg of lasalocid daily. Based upon analyses of forage mineral composition (.53, .25, .14, .3 and 2.5% of dry matter for Ca, P, Mg, Na and K, respectively), all macrominerals except Mg were in sufficient quantities to meet the requirement for lactating cows. Lasalocid supplementation did not affect serum Mg, K or Zn concentrations (P greater than .05). During the April sampling, serum Ca was higher (P less than .05) and serum Na was lower (P less than .05) in cows supplemented with lasalocid compared with controls. The molar proportion of acetate was decreased (P less than .05) in ruminal fluid of cows fed lasalocid by d 56 (February 11); the molar proportions of acetate and butyrate were decreased (P less than .05), which decreased (P less than .05) the acetate: propionate ratio by d 84 (March 11) of supplementation. This study suggests that lasalocid is effective in altering ruminal VFA and serum mineral concentrations in cows grazing small grain forages.  相似文献   

19.
Alfalfa (Medicago sativa L.) persistence and forage and cow-calf production were evaluated on pastures containing smooth bromegrass with or without grazing-tolerant or hay-type alfalfa cultivars rotationally stocked in either a season-long or complementary system. In 1997, six 2.02-ha pastures were seeded with smooth bromegrass, a mixture of a grazing-tolerant alfalfa (Amerigraze variety) and smooth brome-grass, or a mixture of a hay-type alfalfa (Affinity variety) and smooth bromegrass to be used in season-long stocking systems. Four 2.02-ha pastures were seeded with smooth bromegrass on 1.21 ha of each pasture, and mixtures of either the grazing-tolerant or hay-type alfalfa cultivars and smooth bromegrass on the 0.81 ha of each pasture to be used in complementary stocking systems. All 10 pastures were divided into 10 paddocks and rotationally strip-stocked at 1.98 cow-calf units/ha with crossbred cows and calves for 120 and 141 d starting May 18, 1998 (yr 1), and May 6, 1999 (yr 2), respectively. Each year, first harvest forage was harvested as hay from 40% of all 10 pastures, this being the portions of the pasture seeded with the alfalfa-smooth brome-grass mixtures for pastures with the complementary stocking systems. In yr 1 and 2, the remaining 60% of each pasture was grazed for the first 44 and 54 d, and 100% of each pasture was grazed on d 45 to 120 and d 55 to 141, respectively. Proportions of alfalfa in the live dry matter of pastures seeded with the grazing-tolerant and hay-type alfalfa cultivars decreased by 70 and 55% in paddocks stocked season-long and by 60 and 42% in paddocks used for complementary stocking (alfalfa cultivar, P < 0.05; stocking system, P < 0.05) in yr 1, but decreased by 72% across cultivars and stocking systems in yr 2. Total (P < 0.08) forage masses in September of yr 1 and in August of yr 2 were greater in pastures in which alfalfa paddocks were stocked season-long than in those with complementary alfalfa stocking. Grazing of alfalfa in grass mixtures increased calf and total cow/calf weight gains in comparison with grazing of smooth bromegrass, but alfalfa persistence, measured as a proportion of the live dry matter, was not affected by alfalfa cultivar.  相似文献   

20.
In a 2-yr study, we evaluated the effect of different forage allocations on the performance of lactating beef cows and their calves grazing stockpiled tall fescue. Allocations of stockpiled tall fescue at 2.25, 3.00, 3.75, and 4.50% of cow-calf pair BW/d were set as experimental treatments. Conventional hay-feeding was also evaluated as a comparison to grazing stockpiled tall fescue. The experiment had a randomized complete block design with 3 replications and was divided into 3 phases each year. From early December to late February (phase 1) of each year, cows and calves grazed stockpiled tall fescue or were fed hay in the treatments described above. Immediately after phase 1, cows and calves were commingled and managed as a single group until weaning in April (phase 2) so that residual effects could be documented. Residual effects on cows were measured after the calves were weaned in April until mid-July (phase 3). During phase 1 of both years, apparent DMI of cow-calf pairs allocated stockpiled tall fescue at 4.50% of BW/d was 31% greater (P < 0.01) than those allocated 2.25% of BW/d. As allocation of stockpiled tall fescue increased from 2.25 to 4.50% of cow-calf BW/d, pasture utilization fell (P < 0.01) from 84 +/- 7% to 59 +/- 7%. During phase 1 of both years, cow BW losses increased linearly (P < 0.02) as forage allocations decreased, although the losses in yr 1 were almost double (P < 0.01) those in yr 2. During phases 2 and 3, few differences were noted across treatment groups, such that by the end of phase 3, cow BW in all treatments did not differ either year (P > 0.40). Calf ADG in phase 1 increased linearly (P < 0.01) with forage allocation (y = 0.063x + 0.513; R(2) = 0.91). However, calf gain per hectare decreased linearly (P < 0.01) as stockpiled tall fescue allocations increased (y = -26.5x + 212; R(2) = 0.97) such that gain per hectare for cow-calf pairs allocated stockpiled tall fescue at 4.50% BW/d was nearly 40% less (P < 0.01) than for those allocated 2.25% of BW/d. Allocating cow-calf pairs stockpiled tall fescue at 2.25% of BW/d likely optimizes its use; because cow body condition is easily regained in the subsequent spring and summer months, less forage is used during winter, and calf gain per hectare is maximized.  相似文献   

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