Milk substitutes with high ash and macro mineral contents--of importance in loose feces of young calves?

In 3 feeding experiments with 23 calves (age: 5-18 days at trials' start) the effects of high ash and mineral contents in the diet on feces composition (dry matter, pH, concentrations of lactic and volatile fatty acids, mineral contents) and digestibility rates of organic matter, nutrients and minerals as well as on some parenteral parameters (electrolytes in serum, renal excretion) were tested. In all feeding experiments a change-over-design was used, during 10 days each of all calves was fed the control and experimental diet, respectively. In the first trial (8 calves) high ash and mineral contents in the milk replacer were caused by use of a special whey product (25% in the diet), in the second experiment (n = 7) comparable ash and macromineral concentrations were achieved by adding minerals to the basic diet, in the third trial (n = 8) the whey product was used in a lower proportion (15% of the diet). Ash concentrations in diet (g/kg dry matter): 68 versus 138 (trial 1), 75 versus 135 (trial 2), 75 versus 93 (trial 3). The differences in the ash contents were based mainly on differences in the sodium and potassium concentrations.     

Dynamic changes of fatty acids and minerals in sow milk during lactation

The objective of the present study was to explore the changes in fatty acids (FAs) and minerals composition in sow milk in order to improve the knowledge about FAs and mineral requirements for piglets. The FAs and minerals composition in the sow milk samples which were collected from ten sows during a period of 16 days of lactation was analysed. The proportion of FAs in sow milk has a significant increase in C8:0, C10:0, C12:0, C14:0, C16:0, C14:1 and C16:1 FAs and the sum of saturated fatty acids (SFAs) according to the lactation period (p < 0.05). The proportion of C18:2 cis‐9,12 FA and the sum of polyunsaturated fatty acids (PUFAs) significantly decreased with the advancing of lactation (p < 0.05). The concentrations of minerals, including potassium, copper, manganese and zinc, were higher on day 1 and day 2 than those on day 13 and day 16 (p < 0.05). On the contrary, the lowest concentrations of calcium, sodium, magnesium and iron and the lowest molar calcium: phosphorus ratio emerged in colostrum (p < 0.05). In summary, our results demonstrated FAs profile and minerals concentrations were changed with lactation period. Better understanding of the changes of FAs and minerals may be valuable to swine nutritionists in the commercial industry. In addition, those results provided some meaningful information for sow's diet formulation during lactation.     

Effects of concentrate supplementation on blood mineral concentration of growing upgraded Philippine goats

A total of 32 4‐month‐old‐upgraded Philippine goats with mean bodyweight of 13.5 kg were used to study the effects of concentrate supplementation on mineral status of growing goats. All animals received a basal diet comprised of different forage species. Twenty of the animals were supplemented with concentrate at a rate of 150–200 g dry matter/day while the remaining 12 animals were not supplemented. Blood sampling and bodyweight measurement were done every 2 weeks during the 5 months of experiment. Forage, concentrate and blood sulfur, calcium, phosphorus, magnesium, copper, zinc and selenium concentration were analyzed after wet digestion. Forage mineral contents, except for zinc and selenium, were sufficient for requirements of ruminants. Concentrate mineral contents were much higher than the requirements, but did not exceed the toxic levels. The concentrate supplementation resulted in high (P < 0.05) plasma phosphorus, copper, zinc, whole blood selenium concentrations and bodyweight of growing goats, although some supplemented animals showed plasma zinc concentration below the lower critical level. It was recommended that pellets, glass bolus or capsules that contain deficient minerals, such as zinc and selenium, should be used in the study area.     

Macro and trace elements of 26 browse species growing in semi-arid grazing lands of Eastern Cape,South Africa

ABSTRACT

Leaves and twigs from woody plants provide essential nutrients to range animals. We examined variation in the mineral status of 26 woody species, and the influence of harvesting height as well as the interactions of the main effects on minerals levels. Leaves were harvested from five individual plants per species at two height levels: low (<1 m) and upper (>1.5 m). For trees, all mineral levels showed variation (p < 0.05) between species. For shrubs and intermediate growth forms (between shrubs and trees), mineral levels except potassium (K) and zinc (Zn) were influenced (p < 0.05) by height × species interactions. Most browse species had calcium (Ca) contents (8.5–50 g kg^-1) above the required levels, with the majority of the species having Ca beyond the maximum tolerable limit. Most browse plants had sufficient K, phosphorus, magnesium, manganese, iron and Zn concentrations to meet the requirements for ruminants. Copper was deficient in many browse leaves, thus supplementation should be considered in winter. We conclude that such knowledge is essential for sustainable use of browses as mineral supplements, especially during critical periods when climatic conditions limit the feed value of grasses.     

Life-history parameters of Culicoides (Avaritia) imicola Kieffer in the laboratory at different rearing temperatures

This laboratory study investigates the sub-adult developmental cycle of field collected Culicoides (Avaritia) imicola Kieffer (Diptera; Ceratopogonidae). The period required from blood-feeding field-collected females to the production of progeny adults occupied 34–56 days at 20 °C, 15–21 days at 25 °C and 11–16 days at 28 °C, demonstrating clear temperature dependence. When reared at 28 °C, C. imicola demonstrated higher variability in fecundity (between 2.4 and 20.6 eggs/female) and lower hatching rates (50.0–62.2%), although larval survival rates to pupation were low at all temperatures (20–30%). Similarly, the mean emergence rate from pupae was the highest at lower temperatures. These results highlight the difficulty in establishing and maintaining a laboratory colony of this species from field-collected material and results are discussed in reference to future research directions that may aid this process.     

Noninvasive measurements of ovarian activity in Beira antelope (Dorcatragus megalotis)

As the natural habitat of more and more species becomes depleted, captive breeding programmes have become established to bring species back from the brink of extinction. Monitoring the reproductive status of an individual is essential in order to improve breeding success. Traditional methods have involved stressful blood sampling, and thus noninvasive methods have been proven to be reliable alternatives for monitoring reproductive function in both captive and free‐ranging animals. Subsequently, noninvasive methods have become an invaluable tool in longitudinal studies and conservation efforts, as animals can be observed without, or minimal human contact. The Beira antelope is a small antelope endemic to the northern part of the Horn of Africa. Population numbers of the Beira have been declining over the last few decades due to habitat fragmentation. We show here that the reproductive cycle of female Beira antelopes can be monitored noninvasively, by using faecal samples to analyse oestrogen (fEM) as well as progestagen (fPM) metabolites. The profiles of fPM and fEM of both females showed regular cyclic patterns in which the follicular and luteal phases could be distinguished. The overall mean cycle length is 22 days (range: 21–25 days), with a mean length of the follicular phase of 6 days (range: 4–7 days) and a mean length for the luteal phase being 15 days (range: 12–16 days). The suitability of these noninvasive techniques should assist in optimizing breeding efforts of this endemic small antelope in captivity. Being noninvasive, this method could also be a useful tool for monitoring reproductive function in the dwindling wild populations.     

Tibiotarsus bone characteristics and tibial dyschondroplasia incidence of broilers fed diets supplemented with leucine and valine

Two experiments were conducted to study the effect of standardized ileal digestible (SID) leucine and valine levels on tibiotarsus bone characteristics and the incidence of tibial dyschondroplasia of broilers from day 1 to 21 (Experiment I) and day 21 to 42 post‐hatch (Experiment II). Each experimental phase was evaluated independently. In both experiments, a total of 1,500 one‐day‐old Cobb 500 male broiler chickens were distributed in a completely randomized design 5 × 5 factorial arrangement for a total of 25 treatments. The SID leucine and valine levels were ranged from 10.0 to 19.6 g/kg, and 6.0 to 12.0 g/kg from day 1 to 21 post‐hatch, respectively, while day 21 to 42 post‐hatch ranged from 10.0 to 18.0 g leucine/kg, and 5.2 to 11.2 g valine/kg. Serum calcium and phosphorus, bone concentrations of calcium, phosphorus and ash, diameter and Seedor index of the tibiotarsus were not affected (p > .05) by the treatments at 21 or 42 days of age. There was an interaction (p ≤.06) between the SID levels of leucine and valine on tibiotarsus breaking strength at 21 days, but not at 42 days of age (p > .05). Tibiotarsus breaking strength was maximized in broilers from day 1 to 21 with the dietary levels of leucine and valine at 14.2 and 9.0 g/kg respectively. Dietary leucine levels reduced linearly (p < .05) the hypertrophic zone of tibiotarsus cartilage at 21 days of age. Therefore, leucine and valine supplementation interact positively on bone strength of broilers from day 1 to 21 post‐hatch. Leucine can be a useful amino acid for reducing the hypertrophic cartilage zone in broilers from day 1 to 21, but not from day 21 to 42 post‐hatch.     

Effects of mineral salt supplement on enteric methane emissions,ruminal fermentation and methanogen community of lactating cows

We evaluated the effects of mineral salt supplement on enteric methane emissions, ruminal fermentation and methanogen community of dairy cows over a whole lactation period. Ten Holstein cows fed a total mixed ration (TMR) diet were randomly allocated into two groups, one supplied with mineral salts as the treatment group and the other as the control group. The methane measurement showed that the ingestion of mineral salts lowered enteric methane emissions significantly (P < 0.05), with an average of 10.5% reduction over the whole lactation period. Ruminal fermentation analysis showed the mineral salt intake could significantly decrease the acetate : propionate ratio (P < 0.05). Real‐time PCR assay showed that rumen methanogen abundance significantly reduced in the treatment group (P < 0.05) but was not significantly influenced by mineral salt intake over the whole lactation period. Intergroup methanogen community composition was influenced slightly by mineral salt intake; however, significantly different intragroup profiles were apparent throughout the whole lactation period, according to denaturing gradient gel electrophoresis analysis. In conclusion, these results suggested that the effective mitigation of enteric methane emissions by mineral salt intake could be attributed to decreased density of methanogenic archaea and that fluctuations in methane emission over the lactation period might be related to Methanobrevibacter diversity.     

Assessment of tissue development in fattening quails using the stable isotope technique

We aimed to study the behaviour of tissue renewal in blood, pectoral muscle and keel of fattening quails during their growth and adulthood through carbon‐13 turnover using the stable isotope technique. Three hundred male European quails were randomly subjected to six treatments. Diets fed to animals were initially based on corn and soybean meal and were replaced at 0, 7, 14, 21, 28 and 35 days of age with diets of rice grits and soybean meal. These diets have distinct isotopic signals and over time it changes; the tissue will incorporate dietary signal, and then, we can measure the return time for each tissue in each age. Treatments were T1 (0 to 21 days), T2 (7 to 35 days), T3 (14 to 42 days), T4 (21 to 56 days), T5 (28 to 63 days) and T6 (35 to 70 days). Carbon‐13 turnover in tissues of the birds at the above‐mentioned time periods was calculated using the first‐order exponential function. The values of half‐lives were 2.6, 3.6, 5.4, 6.3, 9.0 and 9.8 days for blood and 2.0, 1.7, 4.8, 6.7, 6.9 and 6.6 days for pectoral muscle in treatments T1, T2, T3, T4, T5 and T6 respectively. The half‐lives for the keel in treatments T2, T3, T4, T5 and T6 were 2.0, 5.4, 7.7, 8.9 and 15 days respectively. Thus, half‐life in sampled tissues generally increased with age of birds. Initially, the tissue half‐lives are influenced by growth, and at the end of the growth cycle, the breast muscle tissue was the most metabolically active in either periods, followed by blood and the keel. All tissues showed a sigmoidal growth curve, which can be confirmed by half‐life as a function of age.     

Effects of two different rearing protocols for Holstein bull calves in the first 3 weeks of life on health status,metabolism and subsequent performance

The aim of this study was to investigate the impact of weight gain of calves within the first 3 weeks of life on health status and subsequent performance. Holstein bull calves were reared either intensively (IR; individual hutches and ad libitum milk feeding for the first 3 weeks of life; n = 24), or according to the established protocol [ER; 4 l milk/day in hutches during week 1 and 720 g/day milk replacer (MR) from day 8 to 21 in a group pen; n = 24]. Water, hay and concentrates were freely available to all calves. From week 4, calves of both groups were housed together in a group pen and fed 720 g MR/day; step‐down weaning was performed between week 5 and 10. Key metabolic blood parameters were analysed on day 2, 12, 21 and 70 of life. After weaning, all animals were fed concentrates and corn silage until slaughter at an age of 8 months. Within the first 3 weeks, average daily weight gain was threefold higher in IR calves in relation to ER calves (1.28 vs. 0.38 kg/day, p < 0.001). Neither incidence nor duration of scouring differed significantly between groups. Starter intake (week 4–10) was higher in IR calves in relation to ER calves (49.7 vs. 38.0 kg/calf, p = 0.006). Serum glucose, urea, albumin and insulin were higher at an age of 21 days in IR calves in relation to ER calves; no differences were obvious at an age of 70 days. Plasma GH and IGF‐I concentrations revealed an uncoupling of the somatotropic axis in ER calves within the first 3 weeks of life. At slaughter, body weight of IR calves tended to be higher than that of the ER calves (320 vs. 309 kg, p = 0.07). In conclusion, intensive feeding and individual housing during the first 3 weeks of life had positive long‐term effects on subsequent performance.     

Xanthophylls increased HDLC level and nuclear factor PPARγ, RXRγ and RARα expression in hens and chicks

This study was designed to investigate effects of xanthophylls on serum lipid profile (triglyceride, TG; cholesterol, CHO; high‐density lipoprotein cholesterol, HDLC; and low‐density lipoprotein cholesterol, LDLC) and nuclear factor (peroxisome proliferator‐activated receptor gamma, PPARγ; PPAR gamma coactivator 1 alpha, PGC1α; retinoid X receptor gamma, RXRγ; and retinoic acid receptor alpha, RARα) gene expression of breeding hens and chicks. In experiment 1, 432 hens were divided into three groups and fed diets supplemented with 0 (as control group), 20 or 40 mg/kg xanthophylls. Blood was sampled at 7, 14, 21, 28 and 35 days of trial. Liver, duodenum, jejunum and ileum were sampled at 35 days of trial. Results showed that serum HDLC level of hens was increased after dietary 40 mg/kg xanthophyll addition for 21, 28 and 35 days, while serum TG, CHO and LDLC were not affected. Xanthophyll addition also increased PPARγ expression in jejunum, RXRγ expression in duodenum and jejunum, and RARα expression in liver and duodenum. Experiment 2 was a 2 × 2 factorial design. Male chicks hatched from 0 or 40 mg/kg xanthophyll diet of hens were fed diet containing either 0 or 40 mg/kg xanthophylls. Liver, duodenum, jejunum and ileum were sampled at 0, 7, 14 and 21 days after hatching. Blood samples were also collected at 21 days. Results showed that in ovo xanthophylls elevated PPARγ in duodenum and jejunum, and RXRγ and RARα in liver of chicks mainly within 1 week after hatching, while dietary xanthophylls increased serum HDLC level and PPARγ and RXRγ in liver from 2 weeks onwards. In conclusion, our research suggested xanthophylls can regulate serum lipid profile and nuclear factor expression in hens and chicks.     

Chelated mineral supplementation in the barren mare: A preliminary trial

Twenty-four Thoroughbred mares with breeding histories of having been barren for at least the previous 12 months were evaluated in a double-blind feeding trial to determine the effects of chelated mineral supplementation upon subsequent breeding performance. At the start of the trial (Day 0), mares were split into three dietary treatment groups of eight mares each and fed: (a) control diet with macro- and microminerals fed at NRC recommended levels for maintenance of the mature horse, (b) chelated minerals supplementation and (c) inorganic minerals supplementation at levels equal to Group B. Sixty days after initiation of the trial, there were no differences (P>0.05) between age, endometrial biopsy classification, calculated body weight and body condition score for mares between dietary treatment groups. A breeding performance trial was initiated at this time (Day 60). The number of first cycle and cumulative (i.e. over 3 estrous cycles) conceptions, number of first cycle and cumulative pregnancies and the number of total embryonic losses were not different (P>0.05) between the control and either the chelated mineral or the inorganic mineral groups. There were no harmful effects observed from feeding the chelated minerals 60 days prior to, and during, this breeding trial.     

ORIGINAL ARTICLE: Effect of the level of cholecalciferol supplementation of broiler diets on the performance and tibial dyschondroplasia

A study was conducted to evaluate four different cholecalciferol levels (NRC; modified), using diets supplemented with 200 (control), 1500, 2500 or 3500 IU/kg of cholecalciferol (VIT‐D3). Each treatment was assigned to 3 pens of 17 broiler chicks of a commercial strain grown in an open‐sided house with sidewall curtains. At 21and 42 days, BW and feed conversion (FCR) were determined. At 42 days, five birds per pen were slaughtered to evaluate tibia and toe ash of the right leg, and incidence and severity of tibial dyschondroplasia (TD) of the left tibia and also measured dressing percentage and breast meat yield. Serum calcium and phosphorus concentrations were also determined. Haemagglutination inhibition antibody titre against Newcastle disease virus and lymphoid organs weight/body weight ratio were also determined. At both 21 and 42 days, the BW of birds fed 1500 IU/kg to 3500 IU/kg of VIT‐D3 was significantly greater than birds fed 200 IU/kg. Similarly, better FCR was observed in birds those fed diets of high level of VIT‐D3. No significant difference was observed for mortality at any age. Better dressing percentage and breast meat yield were noted in birds fed diets containing 2500 or 3500 IU/kg VIT‐D3. Both tibia and toe ash contents were increased (p < 0.05) progressively with increased concentrations of cholecalciferol in feed. The incidence of TD (percentage of birds having TD scores greater than zero) was significantly (p < 0.05) influenced by level of 3500 IU VIT‐D3/kg at 42 days. The severity of TD in birds fed diets containing 200 IU/kg VIT‐D3 was apparently higher than birds fed diets with higher levels of VIT‐D3. Concentrations of calcium and phosphorus minerals in the serum increased progressively with the high level of VIT‐D3 supplementation to birds at both 21 and 42 days of age. Feeding levels of 1500 or 3500 IU of vitamin D3 did positively affect the immune system within the parameters measured. It may be concluded that performance, bone mineralization, blood chemistry and immunity against disease in broilers could be maintained when supplementing high level of VIT‐D3 incorporated in broiler diets.     

Effect of trace mineral proteinates on growth and skeletal and hoof development in yearling horses

Fifteen yearlings, nine Thoroughbreds and six Quarter Horses, were used in a feeding trial to determine whether proteinated trace minerals were utilized advantageously over inorganic trace minerals for growth and development when included in the diet at normal supplementation levels. The animals were assigned randomly within breed and gender subgroups to one of two treatments. Group A received a 12% protein (as fed) concentrate containing a trace mineral premix providing inorganic trace minerals at concentrations appropriate to supplement Coastal Bermuda grass (Cynodon dactylon) hay and provide NRC¹ or higher trace mineral intakes. Group B was provided the same concentrations of trace minerals but the Cu, Mn, and Zn were provided via a commercial proteinate. The concentrates were fed to appetite individually, twice daily during a 1.5-hour feeding period. The hay was group-fed in drylot paddocks at 1.0 kg/100 kg BW daily. The animals were housed three or four animals per paddock. Weight and body and hoof growth measurements were taken at the start of the experiment and at 28-day intervals for 112 days. Radiographs of the third metacarpal were made for estimating bone mineral and hoof samples were collected at the start and completion of the experiment. The yearlings gained 0.77±0.03 and 0.79±0.03 kg/d for the inorganic and proteinate groups, respectively. None of the body measurements were affected by diet (P > 0.10) except hip height gain which was higher for the animals receiving the proteinated minerals (7.0 vs 4.7 cm, P = 0.023). Hoof growth was greater for yearlings fed the mineral proteinate than for those fed the inorganic minerals (4.98 vs 4.78 cm, P = 0.016), and colts had greater hoof growth than did fillies (5.00 vs 4.72 cm, P = 0.003). Diet and gender did not affect hoof strength (P > 0.10), but Quarter Horses had greater hoof strength than Thoroughbreds (98.2 vs 88.8 kg, P = 0.046). No differences in bone mineral content or bone mineral deposition were detected (P > 0.10).     

Combination of phytase and citric acid,but not phytase alone,ensures regular rates of growth and bone mineralization in quails under severe phosphorus restriction

An experiment was conducted to evaluate the effects of phytase (PHY), alone or in combination with citric acid (CA), on growing Japanese quails under moderate and severe phosphorus (P) restriction. For this, 504 one‐day‐old female quails were distributed in a completely randomised design with seven treatments and six replications. Treatments consisted of the following diets: (a) positive control (PC): formulated according to quails nutritional requirements; (b) negative control 40% (NC₄₀): PC with 40% less aP; (c) NC₄₀+PHY; (d) NC₄₀+PHY+CA; (e) negative control 65% (NC₆₅): PC with 65% less aP; (f) NC₆₅+PHY; (g) NC₆₅+PHY+CA. Phytase and CA were included at 300 FTU/kg and 40 g/kg, respectively. Performance, bone mineralization and plasma mineral concentration were evaluated at day 35; calcium (Ca) and P metabolism, between days 36 and 39. No significant differences in performance, plasma Ca and P were detected between quails fed PC or NC₄₀; however, NC₄₀ decreased tibia ash (p < 0.01). Treatment NC₆₅ impaired daily weight gain (p = 0.01), tibia ash (p < 0.01), and tibia optical densitometry (p = 0.03), as well as modified plasma Ca (p < 0.01) and P (p = 0.03) concentrations when compared to PC. Both NC₄₀ and NC₆₅ reduced P excretion (p < 0.01). Phytase alone restored tibia ash of NC₄₀ quails to regular rates. Nevertheless, only PHY and CA combined returned plasma P, tibia ash, tibia optical densitometry, and daily weight gain of quails fed NC₆₅ to similar values as those observed in PC. In conclusion, PHY alone suppresses the negative effects of moderate P restriction in growing Japanese quails, but fails in this task under severe P restriction. In such a situation, only the combination of PHY and CA ensures regular rates of growth and bone mineralization. This concept should be better explored by producers in order to take full advantage of the reduction in P excretion achieved by lowering dietary P concentrations.     

Energy requirements of early‐weaned Dorper cross‐bred female lambs

The net and metabolizable energy (NE and ME) requirements of Dorper cross‐bred female lambs with BWs of 20–35 kg were assessed in a comparative slaughter trial. Thirty‐five Dorper × thin‐tailed Han cross‐bred female lambs weaned at ~50 days of age (20.3 ± 2.15 kg BW) were used. Seven randomly selected lambs were slaughtered at the start of the trial (baseline group). An intermediate group consisting of seven randomly selected lambs fed ad libitum was slaughtered when the lambs reached an average BW of 28.5 kg. The remaining 21 lambs were allotted randomly to three levels of dry matter intake: ad libitum or restricted to 70% or 40% of the ad libitum intake. All the lambs were slaughtered when the sheep fed ad libitum reached a BW of 35 kg. Total body energy, nitrogen, fat, ash and moisture content were determined. In a digestibility trial, an additional 15 Dorper × thin‐tailed Han cross‐bred female lambs (28.7 ± 1.75 kg BW) were housed in metabolism cages and used in a completely randomized design experiment to evaluate the ME value of the diet at the three feed intake levels. The maintenance requirements for NE and ME were 245.5 and 380.3 kJ/kg metabolic shrunk body weight (SBW^0.75) respectively. The partial efficiency of energy use for maintenance was 0.645. The NE requirements for growth ranged from 1.18 to 5.18 MJ/d for the lambs gaining 100–350 g/d from 20 to 35 kg BW. Partial efficiency of ME for growth was 0.44. In conclusion, the current study suggests that the NE requirement for maintenance and growth of Dorper early‐weaned cross‐bred female lambs is lower than the current AFRC and NRC recommendations.     

Whole-body mineral composition of entire male and female pigs depositing protein at maximal rates

Thirty-six entire male and female high genetic merit Large White × (Landrace × Large White) pigs were used in a serial slaughter study spanning the liveweight range 25 to 110 kg. The animals were given a high-quality nutrient-dense diet ad libitum and deposited protein at near-maximal rates (around 150 and 170 g/day for the gilts and boars, respectively). The mineral concentrations of the diet exceeded stated requirements for the pig. The whole-body contents of calcium, phosphorus, sodium, potassium and magnesium were determined and related to the empty body weight, lipid-free body weight or whole-body protein. There was an effect of sex of pig (P< 0.05) only on the amounts of sodium and potassium per unit whole-body protein. Calcium, phosphorus and magnesium, were retained isometrically with lipid-free body mass whereas the allometric model indicated that the amounts of sodium and potassium per unit lipid-free body declined significantly (P<0.05) as the animal grew. Functions describing the retention of minerals in the rapidly growing pig are given and can be used in the factorial estimation of mineral requirements.     

微量元素添加模式对肉鸡生长性能、微量元素代谢和血浆抗氧化性能的影响

本试验旨在研究不同微量元素添加模式对肉鸡生长性能、微量元素代谢和血浆抗氧化性能的影响。选取720羽1日龄科宝(Cobb-500)肉鸡,随机分为4个组,每个组10个重复,每个重复18只鸡。行业标准组:按照农业行业标准NY/T 33—2004添加铜、铁、锌和锰。NRC标准组:按照NRC(1994)推荐量添加铜、铁、锌和锰。NRC比例组:实测基础饲粮中铜、铁、锌、锰的含量,以过量最多的铜(相对于NRC标准)的倍数补齐其余3种元素。相对生物学效价组:假设基础饲粮中微量元素的生物学利用率为额外添加硫酸盐的30%,对其含量进行校准后按照NRC比例组的方法添加。微量元素都以硫酸盐形式添加,试验期42 d。结果表明:1)不同微量元素添加模式未对肉鸡生长性能和死亡率造成显著差异(P0.05)。2)21日龄时,NRC比例组肉鸡十二指肠铜转运蛋白1(Ctr1)的mRNA相对表达量显著高于其余各组(P0.05),NRC比例组和相对生物学效价组肉鸡十二指肠二价金属转运蛋白1(DMT1)的mRNA相对表达量显著高于其余2组(P0.05);42日龄时,NRC标准组和相对生物学效价组肉鸡十二指肠DMT1的mRNA相对表达量显著高于其余2组(P0.05);各组间21和42日龄肉鸡十二指肠锌转运蛋白1(Zn T1)和锌转运蛋白5(Zn T5)的mRNA相对表达量没有显著差异(P0.05)。3)21日龄时,NRC比例组和相对生物学效价组肉鸡血浆总抗氧化能力(T-AOC)显著高于其余2组(P0.05);42日龄时,与相对生物学效价组相比,NRC比例组肉鸡血浆过氧化氢酶(CAT)活性显著下降(P0.05)。4)粪便中微量元素浓度和饲粮的微量元素添加浓度存在显著的正相关关系(P0.05)。由此可见,从微量元素吸收效率和肉鸡血浆抗氧化性能来看,考虑基础饲粮微量元素相对生物学效价并按NRC比例添加是更适宜的添加模式,同时减少了粪便中微量元素的排泄。     

Influence of phytase added to a vegetarian diet on bone metabolism in pregnant and lactating sows

The purpose of the study was to find out if the supplementation of phytase to a diet of gestating and lactating sows has any effects on performance and bone parameters of the animals. Forty primiparous gilts were assigned into four groups: group A with phytase [4.2 g total phosphorus (P)/kg (gestation) and 4.5 g total P/kg (lactation)], group B without phytase (with phytase supplementation in diet for rearing) and same P content as group A, group C without phytase and higher P contents [5.0 g total P/kg (gestation) and 5.5 g total P/kg (lactation)] and group D with the same diet as group B (no phytase during the rearing). A 6-phytase was used in this trial (750 FTU/kg diet). The four diets were fed during gestation and lactation. Faeces were collected to determine apparent digestibility of minerals. Blood samples were taken to analyse minerals and bone markers. After weaning the sows were slaughtered and the bones of one hind leg were prepared to measure bone mineral density (BMD) and bone mineral content (BMC) of the tibia. Bone ash and mineral content of the phalanx III were determined. Mean P concentrations in serum decreased during gestation and lactation. But there were no significant differences between the groups. Bone formation marker bone-specific alkaline phosphatase decreased at the beginning of lactation whereas bone resorption marker serum crosslaps increased. The BMD and BMC of the tibia were slightly higher in the groups fed higher concentrations of P and phytase. The ash and mineral contents of the phalanx were the highest for the group fed the highest concentration of P. The apparent digestibility of P increased during gestation mostly in group A (57%--> 69%). In conclusion, high P content and addition of phytase to the diet induced a slightly higher ash content of the bones. It is of high importance, that sows during gestation absorb enough P, to avoid lamenesses and sudden fractures. As not many studies with phytase have been performed during gestation and lactation in sows yet, we can recommend, that phytase as supplement can be used to keep P in the diet at a lower level without negative consequences for bone health.     

Mineral Content of Forages Grown on Poultry Litter-Amended Soils

Large quantities of poultry litter are applied each year to pastures in Arkansas and Oklahoma. Our objective was to monitor mineral concentrations in forages grown on poultry litter-amended soils and compare them with mineral requirements for gestating and early lactating beef cows. A total of 65 forage samples were gathered from four farms in northwest Arkansas and northeast Oklahoma from April 2000 to March 2002. Mean forage mineral concentrations were compared with beef cattle requirements using a two-tailed t test. Two-year average forage Ca, P, K, S, and Fe concentrations from each farm exceeded (P<0.05) gestation and lactation requirements, but forage Zn concentrations from one farm did not differ (P>0.05) from gestation and lactation requirements. On individual sampling dates, concentrations of Ca, P, K, and Zn rarely fell below lactation requirements. Mean forage Mg concentrations from one farm exceeded (P<0.05) lactation requirements, but those from the other three farms exceeded (P<0.05) gestation but not (P>0.05) lactation requirements. Mean tetany ratios from all farms were below (P<0.05) the tetany threshold of 2.2, but forage from two farms surpassed the tetany threshold during Spring 2000, and one sur-passed it during Spring 2001. Average forage Cu concentrations were below (P<0.05) requirements on one farm and did not differ (P>0.05) from the requirements on three farms. Forages from pastures fertilized with broiler litter may meet most but not all mineral requirements of beef cattle, and supplementation of specific minerals, particularly Mg and Cu, may be necessary.