Phosphorus Intake and Excretion on South Carolina Dairy Farms

The objective of this study was to survey dairy farmers to determine P levels in feed and manure. Feed and manure samples were collected from 19 Holstein, six Jersey, and two Guernsey farms in South Carolina. Samples from the Jersey and Guernsey herds were pooled. Samples were dried and analyzed for N and P. Amounts of all feeds were recorded; then, nutrient intake was determined. Dairy Herd Improvement records were used to determine the milk yield and fat content and, subsequently, the P requirement. Nineteen of 27 herds (70%) were fed more P than required according to nutrient requirements established by the NRC. The average P intake was 94.9 g (0.48% of diet DM) compared with the average requirement of 78.3 g (0.41% of diet DM). There were correlations between dietary and fecal P (R² = 0.46) and between CP and P intake (R² = 0.62). There was not a significant correlation between excess P intake and milk yield. In summary, many dairy producers overfeed P. Feeding dietary P at recommended levels will optimize milk yield and reduce P excretion on dairy farms.     

Effects of mannan oligosaccharide and an antimicrobial product in nursery diets on performance of pigs reared on three different farms

The objective of this experiment was to compare the effects of dietary mannan oligosaccharide (MOS) and a feed-grade antimicrobial (AM) on growth performance of nursery pigs reared on three different farms (A and B were large-scale commercial farms, and C was located at Michigan State University). On all farms, production was continuous flow by building, but all-in/all-out by room. Within each nursery facility, all pigs on the experiment were in one room. Pigs (Farm A, n = 771, weaning age = 18.4 d; Farm B, n = 576, weaning age = 19.0 d; Farm C, n = 96, weaning age = 20.6 d) were blocked (within farm) by BW and sex and allotted randomly to dietary treatments arranged in a 2 x 2 factorial. The two factors were 1) with and without MOS (0.3% in Phase I, 0.2% in Phases II, III, and IV; as-fed basis) and 2) with and without AM (110 mg of tylosin and 110 mg of sulfamethazine/kg of diet in all phases; as-fed basis). The four nursery phases were 4, 7, 14, and 17 d, respectively. With 35, 20, and 4 pigs per pen on Farms A, B, and C, respectively, space allowances per pig were 0.29, 0.26, and 0.56 m2. Across all farms, the addition of AM and MOS plus AM increased (P < 0.05) ADG (368, 406, and 410 g/d for control, AM, and MOS plus AM, respectively and increased ADFI (661, 703, and 710 g/d for control, AM, and MOS plus AM, respectively) for the entire 42-d experiment. The addition of MOS also increased ADG (P < 0.05) from d 0 to 42 of the experiment (394 g/d). Performance differed depending on farm (P < 0.01). Antimicrobial did not affect growth performance on Farm B, but it increased (P < 0.05) ADG on Farms A and C, ADFI on Farm A, and G:F on Farm C. Growth improvements with MOS on Farms A and B were not significant; however, pigs on Farm C fed MOS had greater (P < 0.05) ADG, ADFI, and G:F than controls. The results of this study suggest that MOS may be an alternative to tylosin and sulfa-methazine as a growth promotant in nursery diets.     

Prevalence and pattern of antimicrobial susceptibility in Escherichia coli isolated from pigs reared under antimicrobial-free and conventional production methods

OBJECTIVE: To determine and compare levels and patterns of antimicrobial resistance among Escherichia coli isolated from pigs on farms that did not use antimicrobial agents versus pigs produced under conventional methods. DESIGN: Cross-sectional study. Sample Population-35 antimicrobial-free and 60 conventional swine farms. PROCEDURES: Farms were visited once, and fecal samples were collected from 15 finisher pigs if available. One E coli isolate from each sample was tested for susceptibility pattern to 14 antimicrobial agents by use of microbroth dilution. RESULTS: E coli isolates were recovered from 1,381 (97.1%) of 1,422 fecal samples. Herd size was significantly larger for conventional swine farms. Resistance to ceftriaxone, ciprofloxacin, or nalidixic acid was not observed on any of the 95 farms. Three isolates from 2 conventional farms were resistant to ceftiofur. Conventional farms had significantly higher levels of resistance to ampicillin, sulfamethoxazole, tetracycline, and chloramphenicol, compared with antimicrobial-free farms. Fourteen percent of E coli isolates were susceptible or had intermediate resistance to all the tested antimicrobial agents. The 3 most frequent patterns of multiple resistance were streptomycin-tetracycline, sulfamethoxazole-tetracycline, and kanamycin-streptomycin-sulfamethoxazole-tetracycline. CONCLUSIONS AND CLINICAL RELEVANCE: Cessation of antimicrobial use did not appear to result in an immediate reduction in antimicrobial resistance in swine farms. Prospective studies of long-term antimicrobial usage and cessation are needed to estimate the extent to which food animal production may be contributing to antimicrobial drug resistance and might provide a direct measure of the rates of reversibility of antimicrobial drug resistance that might be achieved by curtailing antimicrobial usage.     

乳清粉含量对断奶仔猪生产性能和消化吸收能力的影响

研究不同水平的乳清粉 (5 %、10 %、2 0 % )对断奶仔猪消化吸收能力的影响 ,结果表明 :随乳清粉水平的增加 ,仔猪生产性能随着增加 ,其中各组间ADG达显著水平 (P =0 .0 2 ) ;营养物质消化率也随着乳清粉水平的提高而提高 ,特别是DM和EE的消化率各组间均达显著水平 ;乳清粉从 5 %升至 2 0 %血浆葡萄糖也随着升高 ,差异显著 (P =0 .0 2 ) ,血浆总蛋白各组间差异接近显著水平 (P =0 .0 6 ) ,以 2 0 %乳清分组最高     

Effect of blood metabolites, body condition and pasture management on milk yield and postpartum intervals in dual-purpose cattle farms in the tropics of the state of Veracruz, Mexico

Research was conducted on typical smallholder farms with dual-purpose cattle (DPC) (Bos indicus x B. taurus) in the coastal north-central area of Veracruz, Mexico. The study was divided into two phases. The aim of the first phase was to investigate the effect of blood metabolities, body condition and pasture management on milk yield and postpartum intervals, in order to investigate if the former are suitable indicators of the reproductive and nutritional status of DPC. One hundred and sixty-five calvings of crossbred cows were recorded from January 1992 to November 1994 on 12 small farms. Milk samples were collected twice a week for progesterone analysis. Blood samples and BCS were taken once a month. However, in Phase II emphasis was placed on the effect of pasture management upon reproductive and productive performance of DPC. Records of four farms were obtained from June 1995 to November 1996. Stocking rates were 0.40, 0.87, 0.35 and 1.5 cows/ha for farms A, B, C and D, respectively. Farms A and C used a slow rotation while B and D used a rapid rotation. In Phase I, the changes in BCS during the last month of pregnancy and first month postpartum did not correlate (p > 0.05) with milk yield or reproductive performance. Blood the metabolite profiles were not consistently related to productive or reproductive variables. The effect of farm and season was significant (p < 0.05) on most of the response variables and low productivity on overstocked farms lead to the conclusion that the low reproductive performance of DPC was linked to poor pasture management. During Phase II, farms A (FA) and D (FD) produce more milk than the others. Days to first service, days open, and calving interval were similar for farms B (FB) and C (FC), highest for Farm A, and lowest for Farm D. The forage availability mean was above the critical range of 6-8 kg of dry matter per 100 kg of liveweight (kg DM/100 kg LW) in all farms (range from 6.1 +/- 5.0 to 21.1 +/- 11.2 kg DM/100 kg LW). Farm D had the highest stocking rate (1.5 cows/ha), a rapid rotation (10 paddocks), a good forage availability (7.1 +/- 3.9 kg DM/100 kg LW) with a good quality for a tropical pasture (11.6 +/- 2.4% crude protein), and an economic energy supplementation. These results suggest this type of management could be more widely employed to improve the productivity of DPC on smallholder farms in the Mexican tropics.     

饲喂频率对生长猪饲粮养分消化率的影响

为研究饲喂频率对生长猪总能(GE)和养分的表观回肠消化率(AID)和表观全肠道消化率(ATTD)的影响,试验将24头回肠末端安装简单T型瘘管、平均初始体重为(40.7±1.3)kg的生长猪随机分到M2组(每天饲喂2次)和M12组(每天饲喂12次),每个处理组12个重复,每个重复1头猪。试验期共9 d,包括5 d适应期,2 d粪样收集期和2 d食糜收集期。结果表明:平均日采食量(ADFI)、平均日增重(ADG)和耗料增重比不受饲喂频率的影响(P0.1);饲喂频率对粗灰分、干物质(DM)、粗脂肪(EE)、碳水化合物(CHO)、粗蛋白(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)以及GE的AID无显著影响(P0.1);M2组的粗灰分、DM、EE、CP、NDF和GE的ATTD显著低于M12组(P0.05);M2组EE和ADF(P0.05)、NDF(P0.01)的后肠道消化率显著低于M12组;M2组ADF和CP的ATTD以及GE的后肠道消化率有低于M12组的趋势(P0.1)。由此可见,生长猪饲喂玉米-豆粕型饲粮,GE和养分的AID不受饲喂频率的影响,但增加饲喂频率能提高GE和养分的后肠消化率和ATTD。     

New versus old broiler housing technology: Which leads to greater profit?

The method of matching samples was used to compare the costs and returns associated with broiler housing technology using Agricultural Resource Management Survey data for 2006 and 2011. Farms with housing that included tunnel ventilation and evaporative cooling cells (new technology) were compared with farms with housing that did not include this technology (old technology). Gross farm income, total variable expenses, and total fixed expenses were higher for the new technology farms for both years. New technology farms had greater income over variable expenses and net cash farm income in both years.     

Growth performance, gastrointestinal microbial activity, and nutrient digestibility in early-weaned pigs fed diets containing flaxseed and carbohydrase enzyme

The effects of ground flaxseed (FS) and a multicarbohydrase enzyme (C) supplement on piglet performance, gastrointestinal microbial activity, and nutrient digestibility were investigated in a 28-d trial. The enzyme supplement provided 500 units of pectinase, 50 units of cellulase, 400 units of mannanase, 1,200 units of xylanase, 450 units of glucanase, and 45 units of galactanase per kilogram of diet. Ninety-six pigs were weaned at 17 d of age (BW, 6.1 +/- 0.4 kg, mean +/- SD) and assigned to treatments based on a 2 x 2 factorial arrangement in a completely randomized design, with 6 pens per diet (4 pigs per pen). The diets contained wheat, barley, peas, soybean meal, and canola meal with 0 or 12% FS, and were fed without or with C. Flaxseed was included by changing the levels of the other ingredients to balance the diets for DE and nutrients. Diets had similar nutrient contents and met the NRC (1998) nutrient specifications, with the exception of DE, CP, and AA, which were 95, 94, and 97% of the NRC requirements, respectively. Diets were fed in a 2-phase feeding program (2 wk/phase). Feed intake and BW were measured weekly, and 1 pig per pen with a BW nearest the pen average was bled weekly to evaluate plasma urea nitrogen. On d 28, fresh fecal samples were collected from each pen and 1 pig per pen with a BW nearest the pen average was killed to evaluate intestinal microbial activity and nutrient digestibility. A dietary effect on piglet performance was observed only in wk 3, when the FS diets decreased (P = 0.005) ADG and G:F, tended to decrease (P = 0.070) ADFI, and increased (P = 0.027) plasma urea nitrogen. An interaction between FS and C was observed for ileal digesta viscosity (P = 0.045), such that C increased viscosity in the FS diet but had no effect in the non-FS diet. Flaxseed and C interacted to affect ileal ammonia content (P = 0.049), such that in the absence of FS, pigs fed the diet with C had lower ammonia than those on the diet without C. Flaxseed and C affected other ileal parameters independently. Pigs fed the FS diets had decreased (P = 0.003 to 0.033) anaerobic spore counts, organic acid, DM, CP, and nonstarch polysaccharide (NSP) digestibility compared with pigs fed the non-FS diets, whereas pigs fed the C-supplemented diets had greater (P = 0.009 to 0.061) lactobacilli counts, lactate, DM, and NSP digestibility than pigs fed the unsupplemented diets. In conclusion, FS reduced ileal microbial activity, nutrient digestibilities, and piglet performance in wk 3. The multicarbohydrase supplement increased ileal DM and NSP digestibilities as well as lactobacilli counts and lactate.     

Epidemiology of porcine non-specific colitis on Scottish farms

The objective of this study was to investigate epidemiological risk factors for porcine non-specific colitis (NSC). Forty-seven Scottish pig farms, with and without a clinical history of diarrhoea during the growing period (15-40 kg), were selected. The study included farm visits, clinical inspection of pigs, completion of farm management questionnaires, pathological tests into the cause of the diarrhoea and analysis of the non-starch polysaccharide (NSP) content of feeds. The results from 17 farms designated as NSC and 10 control farms suggest dietary associations with NSC. Farms with NSC fed diets with significantly higher levels of NSPs, especially containing the sugars glucose, arabinose and xylose. Few management factors were identified, although the high prevalence of infectious colitis reduced the power of the study.     

Use of Best Management Practices and Pasture and Soil Quality on Maryland Horse Farms

Agricultural operations, including horse farms, can contribute nonpoint source (NPS) pollution to surface water. The use of best management practices (BMPs) is the most effective way to prevent the movement of pollutants to surface water from nonpoint source pollution. Previous mailed survey studies have assessed the use of BMPs at the county and state level, but a visual assessment of horse farms is necessary to validate survey results. An observational field study was conducted to assess BMP use and soil and pasture quality and to create a model to predict soil erosion on Maryland horse farms. Fifty-one farms were selected based on stocking density (acres per horse [ac horse^-1]), farm use, and presence of water on property. All farms were visited from September through November 2009. In each pasture with grazing horses, the correct use of BMPs was assessed, grass height and vegetative cover were measured, and composite soil samples were collected. Less than half of the 18 assessed BMPs were being used by participants. Although most participants maintained the recommended vegetative cover and grass height, soil erosion was a major problem in pastures. Most farms had optimum soil nutrient concentrations (Ca, K, and P), excessive Mg values, and basic soil pH. Vegetative cover and grass height measurements were positively correlated with stocking density (r = 0.345, P < .0001; and r = 0.291, P < .0001, respectively). Farm use was the only variable that predicted soil erosion on farms (P = .006). Farms used for pleasure were least likely to have soil erosion, whereas farms used for breeding were more likely to have soil erosion (P = .0058). Despite the low-to-moderate adoption of BMPs, the maintenance of recommended vegetative cover and grass height as well as optimum values of soil nutrients indicated participating Maryland horse farms have a low potential for nutrient movement and NPS pollution.     

Chemical composition,energy and amino acid digestibility in double-low rapeseed meal fed to growing pigs

Background:The nutritional value of rapeseed meal may be variable due to the variation of its chemical composition.And a precise understanding of the nutritional value of an ingredient is beneficial for the accurate diet formulation and reduction of feed costs.This study was conducted to determine the chemical composition,digestible energy(DE) and metabolizable energy(ME) content,and apparent ileal digestibility(AID) and standardized ileal digestibility(SID) of amino acids(AA) for growing pigs.Thirteen solvent-extracted double-low rapeseed meal(DLRSM) samples were obtained from the main double-low rapeseed producing areas in China.Methods:The DE and ME contents of the 13 DLRSM samples were measured in growing pigs(six pigs per DLRSM sample,average initial body weight(BW) = 48.3 kg).The AID and SID of AA of 10 DLRSM samples were determined in 12 crossbred barrows(average initial BW = 35.3 kg) by using two 6x6 Latin square designs.Each Latin square comprised one N-free diet and 5 DLRSM test diets.Results:The chemical composition of DLRSM varied among samples,and the coefficient of variation was greater than 10%for ether extract(EE),neutral detergent fiber(NDF),acid detergent fiber(ADF),calcium(Ca),and total glucosinolates.The AA content of DLRSM varied among samples especially for lysine(Lys) and methionine(Met).On a dry matter(DM) basis,the apparent total tract digestibility(ATTD) of gross energy(GE),the DE and ME and the ME:DE ratio of DLRSM averaged 62.39%,2862 kcal/kg and 2723 kcal/kg,and 94.95%,respectively.The mean value of SID of Lys was 70.52% which varied from 66.54-76.54%.The SID of crude protein(CP),Met,and threonine(Thr) averaged 72.81%,82.41%,and 69.76%,respectively.Conclusions:There was great variability in chemical composition especially in the concentration of EE,NDF and ADF,but no significant differences in energy content of the DLRSM samples were observed.In addition,the AID and SID of all AA were relatively similar among DLRSM samples except for that of Lys.     

Evaluation of serological, histological and immunocytochemical methods for the detection of infectious bursal disease virus infection in broiler flocks in New Zealand

AIMS: TO study and compare three diagnostic methods for the detection of infectious bursal disease virus (IBDV) infection. METHODS: Samples of sera and bursae were collected from two flocks from each of two broiler farms (Farms A and B) in which IBD had occurred or was suspected to have occurred. Sera were tested in ELISA and agar gel precipitation tests for the presence of IBD antibodies. Bursae were examined histologically for evidence of IBD lesions. An immunocytochemical test was developed to detect IBDV antigens in sections of bursa. RESULTS: Bursae from serologically negative, 45-day-old birds from Farm A, Flock 1 and from serologically positive 49-day-old birds from Farm B, Flock 1 had histological and immunocytochemical evidence of IBDV infection. Birds from Farm A, Flock 2, sampled 12 months after the sampling of Flock 1, and specific-pathogen-free birds, showed no evidence of IBDV infection by any of the three diagnostic methods. Birds from Farm B, Flock 2, sampled on four occasions, were positive for IBD at 20 days of age by histology and immunocytochemistry, but did not seroconvert until 42 days of age. CONCLUSIONS: Serological testing is not a reliable method for the detection of IBDV infection in New Zealand broiler flocks because antibodies may not have developed to detectable levels by the time of slaughter. Histological examination of bursae allowed the demonstration of IBD-like lesions, but these need to be differentiated from those caused by other agents. The immunocytochemistry test was able to detect early IBDV infection. It provided a rapid, definitive diagnosis and may be useful in control programmes. The results from Farm A demonstrate that strict biosecurity measures can be successful in the eradication of IBDV.     

模猪场猪瘟野毒感染情况调查

利用ELISA方法对广西6个规模猪场送检的1626份猪血清进行猪瘟野毒感染情况调查。结果6个规模猪场均存在猪瘟野毒感染,其中母猪感染率为7.86%~29.21%,平均为17.52%,种公猪感染率为0%~23.52%,平均为11.83%,育肥猪感染率为5%~22.45%,平均为15.5%,断奶仔猪感染率为8.24%~18.57%,平均为12.69%。此检测结果与猪场临床发病情况基本一致,病猪多表现为繁殖障碍型、温和型的非典型猪瘟。     

Cryptosporidium and Giardia associated with reduced lamb carcase productivity

On two extensive sheep farms in southern Western Australia, 111 (Farm A) and 124 (Farm B) female crossbred lambs (2-6 weeks old) were randomly selected and individually identified using ear tags (a numbered tag and radio-frequency tag) at marking. On five separate occasions, faecal samples were collected and live weight, body condition score (BCS), faecal consistency score (FCS), breech fleece faecal soiling score and faecal dry matter percentage (DM%) were recorded. Lamb hot carcase weight (HCW) and dressing percentage were measured at slaughter. Faecal samples were screened by PCR for Cryptosporidium (18S rRNA, actin and 60 kDa glycoprotein [gp60] loci), Giardia duodenalis (glutamate dehydrogenase [gdh] and triosephosphate isomerise [tpi]) and Campylobacter jejuni (16S rRNA). Observation of Eimeria oocysts and faecal worm egg counts (WECs) were performed using a modified McMaster technique. The WECs were adjusted for FCS for analyses. Faecal samples were screened for patent strongylid infections using PCR (specifically ITS-2 nuclear ribosomal DNA for Teladorsagia circumcincta, Trichostrongylus spp. and Haemonchus contortus). Lambs positive for Cryptosporidium at least once had lighter HCWs by 1.25 kg (6.6%) (P=0.029) and 1.46 kg (9.7%) (P<0.001) compared to lambs never positive for Cryptosporidium for Farms A and B respectively. Similarly, dressing percentages were 1.7% (P=0.022) and 1.9% (P<0.001) lower in Cryptosporidium-positive lambs on Farms A and B respectively. Lambs positive for Giardia at least once had 0.69 kg (P<0.001) lighter HCWs and 1.7% (P<0.001) lower dressing percentages compared to lambs never positive for Giardia on Farm B only. Cryptosporidium-positive lambs at the second sampling were 4.72 (P=0.010) and 3.84 (P=0.002) times more likely to have non-pelleted faeces compared to Cryptosporidium-negative lambs for Farms A and B respectively. Breech fleece faecal soiling scores of Cryptosporidium-positive lambs were 3.36 (P=0.026) and 2.96 (P=0.047) times more likely to be moderate to severe (scores 3-5), compared to negative lambs at the second sampling for Farms A and B respectively. Live weight, growth rate and BCS were inconsistently associated with protozoa detection across different samplings and farms. Adjusted WEC was correlated positively with FCS and negatively with faecal DM%, differing between sampling occasions and farms. Campylobacter jejuni prevalence was very low (<1%). Adjusted WEC were not correlated with carcase attributes, growth rates or live weights. This study is the first to quantify productivity consequences of naturally acquired protozoa infections in lambs managed under extensive farming conditions.     

2020年北疆部分地区猪伪狂犬病毒gE蛋白抗体ELISA检测与分析

为了解2020年1—12月北疆部分地区猪伪狂犬病野毒株(PRV-gE)感染情况,采用间接酶联免疫吸附试验(ELISA)法对从北疆4个地区采集的657份猪血样进行PRV-gE蛋白抗体水平检测.结果显示,4个地区PRV-gE抗体阳性率为29.83％(196/657),乌苏地区与其他地区的抗体水平存在一定差异(P<0.05)...     

规模猪场猪瘟野毒感染情况调查

利用ELISA方法对广西6个规模猪场送检的1626份猪血清进行猪瘟野毒感染情况调查.结果6个规模猪场均存在猪瘟野毒感染,其中母猪感染率为7.86%～29.21%,平均为17.52%,种公猪感染率为0%～23.52%,平均为11.83%,育肥猪感染率为5%～22.45%,平均为15.5%,断奶仔猪感染率为8.24%～18.57%,平均为12.69%.此检测结果与猪场临床发病情况基本一致,病猪多表现为繁殖障碍型、温和型的非典型猪瘟.     

Herd-level seroprevalence of swine-influenza virus in Korea

A total of 911 serum samples from 130 herds (an average of nine serum samples per herd) in Korea were examined for antibody to swine H1N1-influenza virus using enzyme-linked immunosorbent assay (ELISA). The list of farms was obtained from the Korean Swine Association, and herds were included from all five of the country’s states. Farms were selected using a random-numbers table for swine within farms and for farms. All serum samples were collected from 22- to 24-week-old finishing pigs between September 2000 and March 2001. By ELISA, 93 out of 130 sampled herds (71.5%) were positive against swine H1N1-influenza virus. Our data suggested that seropositive herds for swine H1N1-influenza virus are distributed diffusely throughout the Republic of Korea.     

Nutrient utilization and manure P excretion in growing pigs fed corn-barley-soybean based diets supplemented with microbial phytase

The effect of high levels of microbial phytase supplementation in diets for growing pigs was studied in a 2‐week performance and nutrient digestibility trial involving 28 growing pigs weighing 16.4 ± 1.06 (mean ± SD) kg. Seven corn‐barley‐soybean meal‐based diets consisting of a positive control (PC) formulated to meet or exceed NRC nutrient requirements; a negative control (NC) with non‐phytate P reduced by 0.1% unit from NRC requirement and fed without or with 500 or 1000 U/kg; a doubled negative control (DNC) with no added inorganic P and fed without or with 2000 or 4000 U/kg. Chromic oxide was added as an indigestible marker and all diets were fed as mash. Pigs fed the PC diet had a higher P digestibility compared with those fed the NC (P < 0.02) and the DNC (P < 0.001) diets. Supplementing the NC diet with pyhtase tended to improve P digestibility (P < 0.10). However, addition of phytase to the DNC diet resulted in linear (P < 0.001) and quadratic (P < 0.03) increases in P digestibility with an overall improvement of 8% and 121% at 4000 phytase U/kg of diet, respectively, compared with the PC and DNC diets. Apparent total tract digestibility of N, OM and DM were higher (P < 0.05) in the PC diet compared with the DNC diet, but not the NC diet (P < 0.10). No effect of phytase addition to NC was observed on Ca, N, DM and OM digestibility. Phytase addition to the DNC diet resulted in a linear increase (P < 0.05) in N, DM and OM digestibility but not Ca. Increasing the levels of phytase supplementation in the NC and the DNC diets linearly decreased fecal P (P < 0.05) content by 45 and 42%, respectively. Adding phytase at 1000 or 4000 U/kg increased P retention (P < 0.05) by 14.3 or 15.6% units, respectively, compared with the PC diet. Urinary P excretion was higher in the group fed the PC diet compared with those fed the NC and DNC diets (P < 0.05). The results of this study show that complete removal of inorganic P from growing pig diets coupled with phytase supplementation improves digestibility and retention of P and N, thus reducing manure P excretion without any negative effect on pig performance.     

规模化种猪场猪瘟免疫情况调研

猪瘟是由猪瘟病毒引起的一种以高热、出血为主要特征的烈性、高度接触性传染病,至今仍在中国广泛流行。接种疫苗是防控该病发生的最根本的方法,为了查清山西省规模化种猪场猪瘟疫苗免疫情况,课题组采用ELISA试剂盒,对8个地市42个规模化种猪场465头哺乳猪、456头保育猪、436头育肥猪、419头母猪进行了猪瘟免疫抗体检测。查明了哺乳猪抗体阳性率平均为70.11%,保育猪抗体阳性率平均为40.57%,育肥猪抗体阳性率平均为50.22%,母猪抗体阳性率平均为69.69%,证明被检猪群免疫抗体不理想,尤其是保育猪抗体水平较低。同时对12个规模化种猪场,4类不同免疫方法免疫猪瘟疫苗的133头哺乳猪、110头保育猪、105头育肥猪、135头母猪进行了免疫抗体检测。结果表明:乳猪在吃奶前超免猪瘟高效细胞苗6头份,21日龄时二免猪瘟高效细胞苗4头份,60日龄三免猪瘟高效细胞苗2头份,母猪产后21 d跟胎免疫效果最好,使保育猪免疫抗体阳性率达到89.29%,有些猪场使用该方法免疫后,使保育猪的死亡率有了明显的降低,生长发育逐渐走向正常;而采用仔猪在断奶后28日龄至35日龄时首免猪瘟普通细胞苗4头份,60日龄二免猪瘟普通细胞苗2头份,母猪产后28 d跟胎免疫的方法效果最差,不宜推广应用。通过对山西一些规模化种猪场猪瘟免疫情况的调研,基本查清了规模化种猪场猪瘟免疫效果和最佳免疫方法,可为养猪场防控猪瘟提供依据。