Initial research on the use of mixed corn grain and stalk silage in broiler fattening

The suitability of a corn and cob maize silage (CCM) as a component rich in energy in the fattening ration was investigated in a growth experiment with male broilers. The CCM silage with a dry matter content of 60.2% contained the following substances determining its value (per 1 kg dry matter of the feed): 102 g crude protein, 61 g crude fibre and 682 energetic feed units for chickens (EFUc). CCM silage was either fed as a component of a feed mixture consisting of 70.5% CCM silage and 29.5% protein concentrate (all values of original substance) or both components of the ration were fed to broilers separately. The protein concentrate was composed as follows (values per kg): 650 g soybean oilmeal, 110 g fishmeal, 85 g tankage from rendering plants, 55 g torula yeast, 70 g mineral mixture and 30 g of a mixture of biologically active substances. The broilers of the control group received commercial fattening feed for broilers with coarse maize meal as cereal component. The feed mixture with CCM silage and separate CCM silage were accepted readily. When CCM silage and protein concentrate were offered alternatively, the same amount of CCM silage was consumed but 8% less protein concentrate. The broilers fed with CCM silage plus protein concentrate reached 96-97% of the live weight of the control animals (1.952 g/animal, 49th day), which received conventional feed, although their net energy intake was 10% lower. This proves a more favourable net energy expenditure for the test groups fed with CCM silage.     

Concentrate composition for Automatic Milking Systems — Effect on milking frequency

The purpose of this study was to investigate the potential of affecting milking frequency in an Automatic Milking System (AMS) by changing ingredient composition of the concentrate fed in the AMS. In six experiments, six experimental concentrates were tested against a Standard concentrate all supplied in the amounts of 5 kg/cow/day. Fifteen cows were fed the experimental concentrate and another 15 cows the Standard concentrate for 14 days and then for the next 14 days the cows were fed the opposite diets to be their own control. The change from one mixture to the next was done over only one day. In each experiment the 30 cows were composed of 12–14 of Danish Holstein, 8–10 of Danish Red and 8 were Jerseys. Basal mixed ration (MR) was fed ad libitum and intake was recorded individually. The effect of the different concentrates on intake and production was evaluated within experiment against the Standard concentrate. A marked effect was found on the number of visits of the cows in the AMS and the subsequent milk production in relation to composition of the concentrate. The composition of the concentrates also influenced the composition of the milk and the MR intake. Based on the overall responses the cows preferred a mixture containing Barley and Oats. Also Wheat based concentrate appeared to be preferred to concentrate based on Maize or Barley and the cows did not like the Fat rich or the pure Artificially dried grass concentrate used in the experiment.     

Interrelationship between hypersensitivity to soybean proteins and growth performance in early-weaned pigs.

The objective of this growth trial was to determine the interrelationship between immunological criteria, gut morphology, and performance of starter pigs fed soybean proteins processed by different methods. One hundred twenty-five pigs were orally infused with 6 g/d of either dried skim milk, soybean meal (48% CP), soy protein concentrate, extruded soy protein concentrate, or experimental soy protein concentrate from 7 to 11 d of age and then fed a diet containing the same protein sources from weaning (d 21) to 35 d of age. All pigs were fed a corn-soybean meal diet containing 10% dried whey, 1.25% lysine, and 3% soybean oil for the remaining 21 d of the experiment. Xylose absorption and anti-soy immunoglobulin G (IgG) titers were measured on d 6 postweaning, and skin-fold thickness after intradermal injection of protein extracts was measured on d 7 postweaning. A total of 25 pigs (five pigs/treatment) was euthanatized on d 7 postweaning. Villus height and crypt depth from duodenum samples were measured. These measurements were obtained to elucidate a relationship between the hypersensitivity responses to soybean products and growth performance of baby pigs. Pigs fed diets containing soybean meal had a lower (P less than .05) rate of gain (d 0 to 14) and villus height, higher (P less than .01) serum anti-soy IgG titers, and increased skin-fold thickness (d 6 and 7 postweaning) after intradermal injection compared with those fed dried skim milk. Pigs fed other soy proteins also had lower ADG from d 0 to 14 postweaning; however, pigs fed moist extruded soy protein concentrate tended (P less than .09) to have higher ADG and improved feed utilization when compared with pigs fed soybean meal (d 0 to 14).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of utilization of local food by‐products as total mixed ration silage materials on fermentation quality and intake,digestibility, rumen condition and nitrogen availability in sheep

Four wethers were used in a 4 × 4 Latin square design experiment to evaluate in vivo digestibility of total mixed ration (TMR) silage with food by‐products for dairy cows, and the ruminal condition and nitrogen (N) balance were examined. Five by‐products (i.e. potato waste, noodle waste, soybean curd residue, soy sauce cake and green tea waste) were obtained. Four types of TMR silage were used: control (C) containing roughage and commercial concentrate, T1:20% and T1:40% containing the five by‐products replacing 20% and 40% of the commercial concentrate on a dry matter (DM) basis, respectively, and T2:40% containing three by‐products (potato waste, noodle waste and soybean curd residue) replacing 40% of the commercial concentrate on a DM basis. The ingredients were mixed and preserved in oil drum silos for 4 months. The TMR silages showed 4.02–4.44% and 1.75–2.19% for pH and lactic acid contents, respectively. The digestibility of DM and neutral detergent fiber, and total digestible nutrient content were higher (P < 0.05) for T2:40% feeding than for C feeding. Urinary nitrogen excretion tended to be lower (P = 0.07) for T2:40% than for C. The results suggested 40% replacing of commercial concentrate by using the three food by‐products can be most suitable for TMR silage.     

Effectiveness of short-term feeding strategies for altering conjugated linoleic acid content of beef

A steer finishing trial was performed to determine the effect of short-term dietary regimens on conjugated linoleic acid (CLA) content of muscle tissues. The experimental design was an incomplete 3 x 2 factorial, with three levels of soybean oil (SBO; 0, 4, and 8% of diet DM) and two levels of forage (20 vs. 40% of diet DM). Forty Angus x Hereford steers averaging 504 +/- 29.0 kg were allotted randomly to one of four treatments for the last 6 wk of the finishing period. Treatments were: 80:20 concentrate:forage control diet (C); 80:20 concentrate:forage + 4% SBO (C4); 60:40 concentrate:forage + 4% SBO (F4); and 60:40 concentrate:forage + 8% SBO (F8). After 42 d on the experimental diets, steers were sacrificed and samples were collected from the chuck, loin, and round muscle groups. Fatty acid (FA; mg/100 mg of FA) composition was determined by gas-liquid chromatography. Data were statistically analyzed with mixed models procedures. The performance and carcass quality model included the effects of SBO and forage. The model for FA composition included the effects of SBO, forage, muscle group, and interactions. Orthogonal contrasts were used to determine linear effects of SBO. There were no differences in growth performance among treatments (P > 0.05). Increasing dietary SBO linearly decreased dressing percent (P = 0.04), and tended to linearly decrease marbling score (P = 0.12) and quality grade (P = 0.08). The only CLA isomer detected in tissue samples was cis-9,trans-11. Addition of SBO to diets linearly increased linoleic acid (18:2n-6; P = 0.04) and tended to linearly increase linolenic acid (18:3n-3; P = 0.10) in muscle tissues. The CLA in lean tissues was decreased (P = 0.005) with SBO-containing diets. These findings suggest that increased PUFA may limit ruminal production of CLA and trans-vaccenic acid (VA) and/or may depress stearoyl-CoA desaturase expression or activity in lean tissues, which in turn limits CLA formation and accretion in tissues. Increasing dietary forage tended to increase 18:0, 18:2n-6, CLA, and 18:3n-3 (P < 0.15), suggesting that increased forage may mitigate toxic effects of PUFA on ruminal biohydrogenation, thereby increasing the pool of CLA and VA available for CLA formation and accretion in tissues. Short-term feeding of elevated SBO and forage levels can alter FA profiles in muscle tissues.     

不同精粗比下柚子皮与苜蓿配比对绵羊饲粮组合效应影响

为了探讨不同精粗比(concentrate:roughage, C:R)下柚子皮与苜蓿配比对绵羊饲粮组合效应的影响,采用体外产气法测定。C:R在20:80下,柚子皮:苜蓿为80:0,70:10,60:20,50:30,40:40,30:50,20:60,10:70,0:80组合;C:R在30:70下,柚子皮:苜蓿为70:0,60:10,50:20,40:30,30:40,20:50,10:60,0:70组合;C:R在 40:60下,柚子皮:苜蓿为60:0,50:10,40:20,30:30,20:40,10:50,0:60组合。24组饲粮组合及3种单独原料分别测定培养2,4,6,9,12,24,36,48,72,96 h内的产气量,并通过24 h产气量(GP_{24 h})和加权估算值计算出各组合的组合效应值(AE)。结果表明:与精料补充料和苜蓿相比,柚子皮的NDF含量较低,产气参数较高。C:R为20:80时,各组AE均为负值,80:0组显著大于0:80组(P<0.05);C:R为30:70时,各组AE无显著差异(P>0.05),30:40、10:60组AE分别为14.74%和3.61%,30:40组AE较好,其他组为负值;C:R为40:60时,0:60组AE极显著大于60:0组(P<0.01),显著大于30:30组(P<0.05),10:50组有大于60:0组的趋势(P=0.079),即0:60、10:50、20:40组AE较大。因此要获得高的AE,高精料(C:R为40:60)时,使用低比例柚子皮(0、10、20);中等精料(C:R为30:70)时,使用中等比例柚子皮(30);低精料时(C:R 20:80)使用高比例柚子皮(80)。     

The effects of inclusion levels of urea-treated potato pulp silage in concentrate and roughage sources on finishing performance and carcass quality in cull beef cows

An experiment was conducted to determine the effects of inclusion levels of potato pulp silage in concentrate (0, 15, 30 or 45%; on a dry matter basis) and roughage sources (rice straw or wheat straw) on finishing performance and carcass quality of cull beef cows. Sixteen Japanese Black (Wagyu) mature cull cows (490 ± 31 kg of BW) were used in this experiment. Increasing the levels of potato pulp silage in concentrate and roughage sources did not significantly affect feed intake in cows. In addition, the final body weight, daily gain and feed : gain ratio were not influenced by the inclusion levels of potato pulp silage in concentrate and the type of roughage. Increasing the inclusion levels of potato pulp silage in concentrate would probably decrease the marbling score. The L* values of the longissimus muscle (LM) tended to respond quadratically ( P  = 0.078) as the inclusion levels of potato pulp silage in concentrate increased, and was lowest for cows fed the concentrate which included 30% potato pulp silage. The a* and b* values of the LM and fat color were not affected by the inclusion levels of potato pulp silage in concentrate. No effects of roughage sources on finishing performance were observed.     

Chemical composition and biological value of spray dried porcine blood by-products and bone protein hydrolysate for young chickens

1. The chemical composition of spray dried porcine blood by-products is characterised by wide variation in crude protein contents. In spray dried porcine blood plasma (SDBP) it varied between 670–780?g/kg, in spray dried blood cells (SDBC) between 830–930?g/kg, and in bone protein hydrolysate (BPH) in a range of 740–780?g/kg. Compared with fish meal, these feeds are poor in Met and Lys. Moreover, in BPH deep deficits of Met, Cys, Thr and other amino acids were found.

2. The experiment comprised 7 dietary treatments: SDBP, SDBC, and BPH, each at an inclusion rate of 20 or 40?g/kg diet, plus a control. The addition of 20 or 40?g/kg of the analysed meals into feeds for very young chickens (1–28?d post hatch) significantly decreased the body weight (BW) of birds. Only the treatments with 40?g/kg of SDBP and SDBC showed no significant difference in BW as compared with the control. There were no significant differences between treatments and type of meal for feed intake, haematocrit and haemoglobin concentrations in blood.

3. Addition of bone protein and blood cell meals to feed decreased the IgG concentration in blood and caused shortening of the femur and tibia bones. However, changes in the mineral composition of bones were not significantly affected by the type of meal used.

4. The blood by-products, which are rich in microelements, improved retention of Ca and Cu only. In comparison to control chickens, significantly better accretion of these minerals was found in treatments containing 20?g/kg of SDBP or 40?g/kg of SDBC.

5. Great variability in apparent ileal amino acid digestibility in chickens was determined. In this respect, some significant differences related to the type of meal fed were confirmed for Asp, Pro, Val, Tyr and His. In general, the apparent ileal digestibility of amino acids was about 2–3 percentage units better in chickens fed on diets containing the animal by products than in control birds.     

Effect of dietary supplementation of hemp seed (Cannabis sativa L.) on meat quality and egg fatty acid composition of Japanese quail (Coturnix coturnix japonica)

This study was conducted in two separate experiments. Experiment I was conducted to investigate the effects of hemp seed (HS) on meat quality traits, and experiment II was designed to determine egg fatty acid (FA) composition in Japanese quail (Coturnix coturnix japonica). In experiment I and experiment II treatments, groups were as follows: (i) control (not included HS0), (ii) 5% HS inclusion to diets, (iii) 10% HS inclusion to diets and (iv) 20% HS inclusion to diets. In experiment I, a total of 192 7‐day‐old‐quail were fed with HS diets for 5 weeks, and end of the experiment I, a total of 64 quail (16 each) slaughtered and meat samples were analysed for meat colour, pH, cooking and thawing loss and FA composition. In experiment II, a total of 120 8‐week‐old laying quail were fed with experimental diets for 6 weeks and egg FA composition were determined. Breast meat cooking loss was significantly lower in 20% supplemented group (p < 0.01). Hemp seed inclusion to diets caused a linear and cubic increase in redness (a*) of hip meat (p < 0.01). Palmitoleic and oleic FAs were decreased with HS addition in breast meat (p < 0.05); however, linoleic and linolenic acid contents of meat were linearly increased (p < 0.01). In experiment II, the linoleic and linolenic FA contents of egg samples were linearly increased with increasing the dietary HS ratio (p < 0.01). Hemp seed addition was provided lower palmitoleic and oleic FAs in quail eggs (p < 0.05). In conclusion, HS supplementation to quail diets may increase quail meat redness and meat and egg yolk omega‐3 FA content and decrease cooking loss of quail meats.     

Effect in sheep of dietary concentrate content on secretion of growth hormone, insulin and insulin-like growth factor-I after feeding

This study was designed to examine the effects of the proportion of concentrate in the diet on the secretion of growth hormone (GH), insulin and insulin‐like growth factor‐I (IGF‐I) secretion and the GH‐releasing hormone (GHRH)‐induced GH response in adult sheep fed once daily. Dietary treatments were roughage and concentrate at ratios of 100:0 (0% concentrate diet), 60:40 (40% concentrate diet), and 20:80 (80% concentrate diet) on a dry matter basis. Mean plasma concentrations of GH before daily feeding (10.00–14.00 hours) were 11.4 ± 0.4, 10.1 ± 0.5 and 7.5 ± 0.3 ng/mL on the 0, 40 and 80% concentrate diet treatments, respectively. A significant decrease in plasma GH concentration was observed after daily feeding of any of the dietary treatments and these decreased levels were maintained for 8 h (0%), 12 h (40%) and 12 h (80%), respectively (P < 0.05). Plasma IGF‐I concentrations were significantly decreased 8–12 h and 4–16 h after the end of feeding compared with the prefeeding level in the 40 and 80% concentrate diet treatments, respectively (P < 0.05). GHRH injection brought an abrupt increase in the plasma GH concentrations, reaching a peak 10 min after each injection, but, after the meal, the peak plasma GH values for animals fed 40% (P < 0.05) and 80% (P < 0.01) concentrate diet were lower than that for roughage fed animals. The concentrate content of a diet affects the anterior pituitary function of sheep resulting in reduced baseline concentrations of GH and prolonged GH reduction after feeding once daily.     

Production of dairy cows fed whole-crop cereals or ryegrass silages supplemented with a fixed amount of concentrate

Abstract

Feed intake and milk production responses to whole-crop cereal silages and ryegrass silage (RGS) supplemented with a fixed amount of concentrate were measured in three 4×4 Latin square-designed experiment with three 17-day periods using 12 Holstein cows. Diets consisted of a fixed amount of concentrate (10 kg) and one of the following silages offered ad libitum: RGS, Mondego wheat silage (MWS), Alva wheat silage (AWS), and triticale silage (TS). Silage dry matter intake and milk yield were significantly higher for RGS. Milk composition was not affected by silage treatment. The whole-crop cereal silages tended to show higher milk concentrations of anteiso C15:0, iso C15:0, C16:1 and C18:1 and lower concentrations of C18:2 and C18:3. This study suggests better response of dairy cows to a single cut RGS than to whole-crop cereal silages harvested in an early stage of maturity.     

Profile of fatty acid lipid fractions of omega-3 fatty acid-enriched table eggs

The omega-3 fatty acid (FA) enrichment of yolk is a key means one of the main objectives to improve the nutraceutical properties of eggs. We evaluated the effect of the dietary inclusion of extruded linseed fed to laying hens on the fatty acid composition of the polar and non-polar lipid classes of the eggs. Two groups of 36 Lohmann White Leghorn layers (65 weeks old) were each fed one of two different diets for a period of 12 weeks. The two diets consisted of a conventional cereal-based diet concentrate (C) and a diet concentrate containing 5% linseed (L). The inclusion of linseed in the diet increased the content of α-linolenic (C18:3n-3), eicosapentaenoic (C20:5n-3) and docosahexaenoic (C22:6n-3) acids in neutral lipids, while a concomitant decrease in arachidonic acid (C20:4n-6) was observed. As regards the polar fraction, the fatty acid composition was slightly affected by the dietary treatments except for C18:0 (+1.14 fold), C18:2n-6 (+1.23 fold), C18:3n-3 (+2.8 fold) and C22:6n-3 (+1.41 fold). Principal component analysis demonstrated that very long-chain FAs were more representative of polar lipids, except for C20:5n-3, while neutral lipids were characterized by dietary n-3 FA (C18:3n-3).     

Brewer's yeast and sugarcane yeast as protein sources for dogs

Brewer's yeast (BY), autolysed sugarcane yeast (ASCY) and integral sugar cane yeast (ISCY) were studied in two experiments as ingredients for dog diets. In the first experiment, 28 dogs were randomly assigned to four diets; one reference diet and three test diets containing 15% of BY, ASCY or ISCY and 85% of the reference diet (as‐fed basis). The digestibilities of the yeasts were calculated by the substitution method. In the second experiment, 35 dogs were randomized to five diets with similar chemical composition but different levels of sugarcane yeast inclusion (0%, 7.5% ASCY, 15% ASCY, 7.5% ISCY and 15% ISCY). In both experiments, the coefficient of total tract apparent digestibility (CTTAD) of nutrients was determined through total collection of faeces. During experiment, two additional analyses of food palatability, nitrogen balance and urea postprandial responses were performed. The data were submitted to analysis of variance, and the means were compared by orthogonal or polynomial contrasts or Tukey's test (p < 0.05). In experiment 1, CTTAD of protein was lower for both sugarcane yeasts than for BY (p = 0.012), as was metabolizable energy content (p = 0.025). In experiment 2, a linear reduction in energy digestibility with ASCY inclusion (p = 0.05) was verified. Furthermore, faecal score and DM content were reduced with ISCY inclusion (p < 0.003). No effect of yeast inclusion on nitrogen balance or postprandial urea response was found. Also, the inclusion of 7.5% of ASCY or ISCY increased diet palatability (p < 0.01). Yeasts present adequate digestibility by dogs, but its effect on faecal formation needs to be considered. No clear advantage for the use of ASCY over ISCY was found. In conclusion, we find that sugarcane yeast is suitable for inclusion in dog food and can enhance the overall palatability of the diet.     

Effect of virginiamycin on in vivo digestibility, rumen fermentation and nitrogen balance

Three experiments were conducted to investigate the effect of virginiamycin. Digestibility was determined with wethers, fed a diet of 0.65 maize silage and 0.35 concentrate on a dry matter basis (Experiment I) or a complete dry feed (Experiment II) at maintenance, and with growing bulls fed a maize silage diet ad libitum supplemented with 7.5 g concentrate per kg live weight (Experiment III). Virginiamycin was incorporated at 0 or 65 ppm in the concentrate and 0 or 25 ppm in the complete dry feed. No significant effect on dry or organic matter digestibility was observed, although digestibilities of protein and ether extract were reduced by virginiamycin in experiments I and II, respectively. Rumen fermentation was studied in experiments I and II. Virginiamycin increased acetic acid concentration and reduced butyric acid concentration in experiment I, but exerted no significant effect in experiment II. An interaction between diet type and virginiamycin was found for the C2/C3 ratio. Nitrogen balance, measured in experiment III, was not affected by virginiamycin.     

日粮中尿素氨化稻草水平对体外培养发酵总产气量、氨态氮和pH值的影响

本试验旨在研究日粮中添加不同比例的氨化稻草及精组比例对体外发酵产气规律的影响。以2头安装有永久性瘤胃瘘管的西门塔尔牛作为瘤胃液供体,以未氨化、4%尿素和6%尿素氨化的稻草为粗饲料,分别与精料混合料配制成6种比例日粮,其中精料与粗饲料的比例为0∶100、20∶80、40∶60、60∶40、80∶20、100∶0。采用体外产气法测定各种日粮体外发酵的产气规律。结果表明:同一尿素氨化水平下,随着精料比例增加,产气量显著增加(P<0.05),并且精料∶粗料为100∶0组极显著高于0∶100组(P<0.01);不同尿素氨化水平下,精料∶粗料为40∶60时,4%尿素氨化组48 h产气量显著高于未氨化组(P<0.05),并且高于6%氨化组,而精料∶粗料为0∶100、20∶80、60∶40、80∶20、100∶0时,3种尿素氨化水平产气量之间差异不显著(P>0.05)。表明使用4%尿素对稻草进行氨化处理、日粮精料∶粗料为40∶60时,日粮的可消化性最好。     

基于主成分分析的精料、构树和全株玉米青贮的组合效应评价

本试验旨在利用主成分分析评价精料、构树和全株玉米青贮以不同比例组合后的组合效应，筛选最佳组合比例。试验设计3个精粗比(40∶60，50∶50，60∶40)，15种日粮组合比例，利用体外模拟瘤胃发酵测定15个组合的瘤胃发酵指标，通过主成分分析法对其进行综合评价。精粗比40∶60时，40∶60∶0和40∶45∶15组的氨态氮(NH₃-N)含量较高；精粗比50∶50时，50∶0∶50，50∶12.5∶37.5和50∶25∶25组的72 h产气量(GP₇₂)较高(P>0.05)，50∶25∶25组的NH₃-N含量最高；精粗比60∶40时，60∶10∶30组的乙酸(AA)、丙酸(PA)和总挥发性脂肪酸(TVFA)浓度显著高于其他各组(P<0.05)。精料∶构树∶全株玉米青贮比例为60∶10∶30，综合主成分值最大。在本试验条件下，日粮中添加构树可以改善肉牛体外瘤胃发酵性能，当精料∶构树∶全株玉米青贮比例为60∶10∶30时，组合效果最佳。     

Encapsulated nitrate replacing soybean meal changes in vitro ruminal fermentation and methane production in diets differing in concentrate to forage ratio

The objective of this study was to evaluate the effects of using encapsulated nitrate product (ENP) replacing soybean meal in diets differing in concentrate to forage ratio on ruminal fermentation and methane production in vitro using a semi‐automatic gas production technique. Eight treatments were used in a randomized complete design with a 2 × 4 factorial arrangement: two diet (20C:80F and 80C:20F concentrate to forage ratio) and four levels of ENP addition (0%, 1.5%, 3.0%, and 4.5% of DM) replacing soybean meal. There was a diet × ENP interaction (p = 0.02) for methane production. According to ENP addition, diets with 80C:20F showed more intense reduction on methane production that 20C:80F. A negative linear effect was observed for propionate production with ENP addition in diet with 80C:20F and to the relative abundance of methanogens Archaea, in both diet. The replacement of soybean meal by ENP in levels up to 3% of DM inhibited methane production due to a reduction in the methanogens community without affecting the organic matter degradability. However, ENP at 4.5% of DM level affected fiber degradability, abundance of cellulolytic bacteria, and propionic acid production, indicating that this level of inclusion is not recommended for ruminant production.     

The Nutritive Value of Lucerne Leaf Meal for Pigs Based on Digestibility and Nitrogen Utilization

Abstract

Digestibility, energy metabolism and nitrogen utilization of a barley-based diet with increasing inclusion of lucerne leaf meal (LLM; 0, 5, 10 and 20%) were studied in a change-over experiment with growing pigs. In addition, digestibility and nitrogen utilization of the diets were evaluated with rats. The apparent digestibility of fibre increased with LLM inclusion, whereas the digestibility of organic matter, crude protein, fat and energy all decreased significantly. There was a significant reduction in the dietary content of digestible and metabolizable energy with increasing inclusion of LLM in the diet. Nitrogen retention and utilization were significantly increased with an increasing inclusion of LLM.     

Nycterohemeral patterns of acid-base status, mineral concentrations and digestive function of lactating cows in natural or chamber heat stress environments

Effects of heat stress on multiparous lactating Holstein cows were evaluated in a continuous design in natural environments (a shade management system vs no shade, n = 6/treatment, early- to mid-lactation cows) and in a single-reversal design in climatic chambers (thermoneutral vs thermal stress, n = 4/treatment, mid- to late-lactation cows). Objectives were to compare effects of nycterohemeral heat stress vs nonheat stress environments on acid-base status, mineral concentrations and rates of ruminal liquid dilution and solid phase digesta turnover. In the shade vs no shade experiment, the complete mixed diet consisted of 38% corn silage and 62% corn-based concentrate mix. In the chamber experiment, the diet consisted of 40% alfalfa haylage and 60% corn-based concentrate mix. In both experiments, respiration rates, rectal temperatures, blood and urine were sampled hourly for 26 h. Measurements of rectal temperature, respiration rate and blood gas composition indicated that chamber heat stress simulated natural heat stress. In both experiments, cows exhibited signs of respiratory alkalosis only during hours of heat stress. Ruminal turnover rates of liquid were measured with chromium-ethylenediaminetetraacetate and solid turnover rates with ytterbium-marked fecal fiber, both dosed through the ruminal cannula. Turnover rates of liquid and solid digesta and total volatile fatty acids were lower in the heat stress vs the thermoneutral environment. The results illustrate the necessity of frequent sampling to characterize nycterohemeral patterns of physiological measurements during heat stress.     

无机硫来源对体外瘤胃发酵的影响

利用短期人工瘤胃发酵装置,研究精粗比为4∶6日粮添加硫磺、硫酸钠、硫化钠等三种来源的硫对瘤胃液pH、挥发性脂肪酸(VFA)产生量的影响。结果表明:硫的添加量明显影响人工瘤胃发酵中有机物的消失率(P<0.05),日粮中添加硫0.5%时,对照组、硫磺、硫酸钠、硫化钠组间瘤胃液pH、日粮中性洗涤纤维(NDF)消失率、氨态氮浓度有明差异(P<0.05),硫来源没有明显影响人工瘤胃中总VFA、丙酸、乙酸浓度(P>0.05);硫酸钠、硫化钠的作用效果优于硫磺试验组。