Promotional effects of nanoparticles on plants北大核心CSCD

随着全球气候变化和人口数量的增长,人们对于植物生产的可持续发展需求更为迫切。纳米技术是21世纪发展最快的前沿科技之一,为促进农业可持续发展最有前景的工具之一。近年来,纳米材料调控植物生长的研究迅速发展,证实了其在传统植物生产中的潜在能力。为明确纳米材料对植物的促生作用及作用机制,本研究就纳米材料的吸收运输、纳米肥料、纳米植物生长调节剂、纳米酶与植物抗逆、纳米材料与光合作用等方面进行了论述,并指出纳米材料在植物生产领域面临的挑战和未来研究重点,强调要系统考虑纳米材料在农业生产中的应用,以期为后续纳米粒子调控植物生产的研究工作理清思路。     

Absence of effects of dietary α‐tocopherol on egg yolk pigmentation

1. Three experiments were carried out in which yolk colour and carotenoid content were measured in hens fed diets containing soyabean oil or tallow and supplemented with 0, 10, 20, 40, 80, 160 or 320 mg tocopheryl acetate.

2. Fat type had no consistent effect on yolk carotenoid content but yolk α‐tocopherol concentrations were lower with the soyabean oil diet.

3. Yolk concentrations of all carotenoids measured and yolk colour were unaffected by dietary α‐tocopherol concentration.     

Environmental effects on steroid hormone concentrations in laying hens’ eggs

Abstract

The hormone content of a birds’ egg may reflect the environmental conditions of the bird. In this study we measured hormone concentrations of eggs from hens living under different housing conditions. Eggs from 16 floor-housed and 16 singly caged hens were analysed for androstenedione and estradiol. The concentrations of these hormones were highest in the yolk of eggs from floor-housed hens (P≤0.05). The concentration of estradiol in the albumen of eggs was highest for caged birds (P≤0.0001). In caged hens, the concentrations of both hormones varied significantly over days in the egg yolk, but not in the albumen. As the concentration of androstenedione and estradiol in the yolk of chicken eggs is environmentally dependent, these hormones may provide a mechanism by which the hen signals the state of the environment to her progeny.     

Sire × pasture program interaction effects on preweaning performance of crossbred beef calves

Records on crossbred calves from the eight crosses between Angus (A) and Hereford (H) cows, and A, H, Jersey, Simmental and Brahman sires, and raised in two pasture programs were used to assess sire × pasture interactions on preweaning traits. There were 518–734 calves from 252–318 dams and 122–166 sires in the data set; numbers vary by traits. Sires, AI or natural service, constituted a representative sample of the breeds. Pasture programs differed principally in the winter period (tall fescue hay vs. corn silage). Heritabilities across and within pastures were: 0.28±0.19 and 0.28 ± 0.19 for birth weight (BW ); 0.08 ± 0.58 and 0.58 ± 0.19 for weaning weight (WW); 0.30 ± 0.41 and 0.71 ± 0.19 for weight adjusted to 205 days (W205); 0.00 ± 0.00 and 0.36 ± 0.15 for daily gain (DG); 0.61 ±0.35 and 0.94±0.25 for frame score (FRAM); 0.14±0.38 and 0.53±0.22 for muscle score (MUSC); and 0.00±0.00 and 0.14±0.21 for conformation score (CONF), respectively. Correlations between progenies of the same sire in different pasture programs are: 1.00±0.00 for BW; 0.13±0.99 for WW; 0.42±0.58 for W205; 0.00±0.00 for DG; 0.65±0.34 for FRAM; 0.27±0.71 for MUSC; and 0.00±0.00 for CONF. Except for birth weight, estimates (although imprecise) suggest that changes in the ranking of sires should be expected to occur between the two environments, possibly in part from incomplete adjustment for changes in season of calving between pasture environments for calves sired by the same sire.     

Modification of the human–broiler relationship and its potential effects on production

The present study was designed to investigate the effects of additional human contact (AHC) on the human–animal relationship (HAR) in broilers and on the birds’ productivity. A total of 1558 broiler one-day-old chicks were distributed into 12 equally sized pens at two different stocking densities (SDs), calculated on estimated weight at slaughter (4 pens with 32?kg/m² and 8 pens with 16?kg/m²). Six groups (2 high and 4 low SDs) received AHC, which consisted of 30-min sessions with visual human contact three days/week. The remaining six groups received as little human contact as possible and served as controls. A touch test was used to assess the human–broiler relationship and the production parameters measured were growth rate, mortality, feed consumption and feed conversion. The AHC treatment had a positive effect on the quality of the HAR but failed to affect any production parameter.     

Storage time‐temperature effects on the odour preferences for uncooked chicken parts

1. Whole broilers and separated legs were stored at ‐12 ± 1 °C, —18 ± 1 °C and — 75 ±2 °C (reference group, whole carcasses only), for up to nine months.

2. Legs cut from the whole birds after removal from store, unpacking and thawing, and legs from the portions were compared in odour preference at four times of examination.

3. After only 1 d the odour of the legs stored as parts at —12 °C was less preferred than that of the reference group; this was also true for legs cut from whole birds after 3 months at the same temperature.

4. After 3 months at — 12 °C the odour of the legs stored as parts was less preferred than the odour of legs obtained from whole birds.

5. Storage of legs as parts at —18 °C resulted in a comparatively less preferred odour after 3 months, while the same was true after 9 months for legs cut from the carcasses.     

Fruit pomaces—their nutrient and bioactive components,effects on growth and health of poultry species,and possible optimization techniques

The ever-growing human population, coupled with the exigent need to meet the increasing demand for poultry meat and egg, has put the onus on poultry nutritionists and farmers to identify alternative feed ingredients that could assure the least-cost feed formulation. In addition, the public desire for nonantibiotic-treated poultry products has also necessitated the ultimate search for potent antibiotic alternatives for use in poultry production. While some identified alternatives are promising, t...     

Physiological effects of different Cd concentrations on maize root architecture and classification北大核心CSCD

In this research, a hydroponics experiment was conducted to apply different concentrations of cadmium (Cd) (0, 5, 10, 25, 50, 100, 200 μmol·L-1) to maize seedlings with two leaves and one new leaf, in order to explore the effects of the different Cd concentrations on the maize seedling growth, Cd absorption kinetics and root morphology and classification. After 5 days of Cd stress, the maize seedings were sampled, the plant height, main root length, aboveground and underground biomass, root architecture, Cd content and photosynthesis and related parameters were measured. It was found that with increasing Cd stress, the plant height, main root length, biomass and tolerance index of shoots and roots, total root length, root surface area, root volume, root forks and root tips all decreased significantly; Root average diameter and root:shoot increased significantly (P<0.05). Meanwhile root parameters (root length, root surface area and root volume) of root diameter classes designated Ⅰ-Ⅲ (0-1.5 mm) showed a decreasing trend, which had a significant (P<0.05) negative correlation with root Cd concentration. The proportion of root length, root surface area and root volume with diameter between 0-0.5 mm showed a downward trend under Cd stress. Under Cd stress, Cd concentration and accumulation in underground and aboveground parts of maize seedlings increased significantly, chlorophyll content decreased, and photosynthesis was inhibited. This study has shown that Cd affected root development mainly by inhibiting the growth and morphology of fine roots, and inhibited photosynthesis, elongation and biomass accumulation of the aboveground and underground parts of the maize seedings. © 2022, Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Quantitative effects of pelleting on performance,gastrointestinal tract and behaviour of meat‐type chickens

1. In an attempt to quantify the effects of “degree” of pelleting, two experiments were conducted. Diets were prepared by mixing together a mash composed mainly of maize (experiment 1) or sorghum (experiment 2) with soft pellets, or soft pellets mixed with hard pellets.

2. The pelleting degrees (PDs) were as follows: 0 mash; 0·5 mixture of soft pellets and mash 1 to 1; 1 soft pellets pelleted once; 1·5 mixture of soft and hard pellets 1 to 1; 2 hard pellets pelleted twice.

3. In experiment 2, the weight and length of the digestive organs were determined as well as digestive enzyme activities. In both experiments, the behaviour recorded was eating, standing, sitting and drinking.

4. Food intake and body weight gain were related to the degree of pelleting in a curvilinear manner. PD had a positive effect up to a peak (1 to 1·5 PD), after which its effect decreased. Food efficiency was not related to PD. In experiment 1, food efficiency of PDs 1 to 2 were superior to PDs 0 to 0·5 and in experiment 2, PDs 1·5 to 2 were superior to PD 0.

5. The relative weight of the gizzard was reduced by pelleting, whereas pelleting increased the relative weight of abdominal fat. The content of the crop was not affected by PD, whereas that of the proventriculus was lowest in the PD 2 group. Gizzard content was inversely related to PD. Pelleting reduced the length of the jejunum and ileum: which were shortened by about 15% with PDs 1 to 2, as compared to PD 0. The weight/length ratio of the jejunum and ileum tended to increase with increasing PD to a peak at PD 1·5, and to decrease thereafter.

6. Trypsin activity in the pancreas and amylase activity in the intestinal content were reduced by pelleting.

7. Chicks fed pelleted diets were less active: they ‘sat’ more and spent less time eating than their mash‐fed counterparts.     

Interactive effects of α-tocopheryl acetate and zinc supplementation on the antioxidant and immune systems of broilers

ABSTRACT

1. A total of 1440 one-day-old Ross 308 male broilers were allocated to 12 dietary treatments to evaluate dose-dependent effects of α-tocopheryl acetate (α-TOA) combined with zinc (Zn) supplementation on humoral and cellular immune responses, antioxidant enzymes, serum and hepatic contents of vitamins and minerals in broilers.

2. Three levels of supplemental α-TOA (0, 150 and 300 mg/kg) and 4 levels of Zn (0, 100, 200 and 400 mg/kg) were combined as a completely randomised design as a 3 × 4 factorial arrangement.

3. Concentrations of serum α-tocopherol and selenium were influenced by the interaction of α-TOA and Zn. The interaction of α-TOA and Zn affected malondialdehyde (MDA) concentration in serum and liver (p < 0.05). Incremental amounts of supplemental Zn augmented the effects of α-TOA in reducing serum and hepatic MDA concentrations.

4. The interaction of α-TOA and Zn on antibody titres (p < 0.05) was such that increasing level of Zn at each α-TOA level led to a linear enhancement in antibody titre. Moreover, dietary supplementation with α-TOA and Zn resulted in an increase in relative weight of lymphoid organs (thymus, bursa, spleen; p < 0.05) along with an increase in humoral and cellular immune responses (p < 0.05).

5. In conclusion, α-TOA with Zn showed interactive effects in improving oxidative stability and humoral immune responses, which could result from their impact on the concentrations of antioxidant vitamins and minerals in tissues.     

Inhibitory effects of recombinant porcine interferon-α on high- and low-virulence porcine reproductive and respiratory syndrome viruses

The inhibitory effects of recombinant porcine interferon alpha (rPoIFN-α) on the propagation of low-virulence PRRSV (lvPRRSV) in MARC-145 cells, and on the progress and severity of high virulence PRRSV (hvPRRSV)-induced infections in pigs, were determined. Pre-treatment of MARC-145 cells with increasing concentrations of rPoIFN-α prior to infection with lvPRRSV decreased the observed cytopathic effects (CPEs) in a concentration-dependent manner. Viral propagation and antibody response were temporarily delayed in swine treated with rPoIFN-α either at the same time as the hvPRRSV challenge was administered or post-challenge. Exposure of challenged animals to rPoIFN-α after the onset of disease symptoms alleviated associated hyperthermia. Variations in lymphocyte subsets indicated that rPoIFN-α treatment might alleviate damage to the immune system or enhance propagation of host cytotoxic T-lymphocytes when the treatment was applied simultaneously with the virus or 1dpc, respectively.     

Short‐term effects of fertilizer and stocking rates on the Bankenveld: 2. Animal production

This article on the short‐term effects of veld fertilization in the Bankenveld, deals with the effects of nitrogenous, phosphatic and potassic fertilization, and stocking rates on beef, mutton and wool production. Increased beef production was obtained by applying nitrogenous (linear to 80 kg N/ha) and phosphatic fertilizer to the veld. Fertilization influenced the production of merino sheep less than that of cattle.

Production per animal decreased and that per unit area increased (to a certain point) as a result of increased stocking rates. The expression of these results as MLU/ha or as ha/MLU influenced the form of the response obtained.

Problems were encountered in utilizing fertilized veld, which influenced the economics of the practice. In spite of poor utilization, on some treatments, it appears that veld fertilization can be profitable in its initial stages.     

Higher feeding diets effects on age and liveweight gain at puberty in crossbred Nelore × Hereford heifers

This study was conducted to determine the age and liveweight at puberty of 120 crossbred beef heifers submitted to four diets to achieve predetermined weight gains (kg/day): 0.5 (G500; n?=?32), 0.75 (G750; n?=?32), 1.0 (G1000; n?=?29), and 1.25 (G1250; n?=?27). Animals were classified depending on their level of crossing between Nelore (N) and Hereford (H): 25%N-75%H, 37.5%N-63.5%H, 43.7%N-56.7%H, 50%N-50%H, and 75%N-25%H. Reproductive evaluation was performed at the beginning and at the end of the experimental period by ultrasonography and hormone analysis. The average age and liveweight at puberty were 388.0?±?1.9 days and 331.4?±?1.3 kg, respectively. Animals from the 25%N-75%H group reached puberty earlier than heifers from other genetic groups supplemented with G1250 diet (P?<?0.05). Heifers with higher degree of Nelore (75%N-25%H) fed with G1000 diet showed estrus 42 days prior to mating, but only 57 % reached puberty at mating (P?<?0.05). Heifers with follicles of higher diameter reached puberty (P?<?0.05) earlier. Higher average daily weight gain showed a positive effect on follicular diameter and IGF-I level at puberty (P?<?0.01). Concentrations of GH were lower in heifers fed G1250 compared to G1000 diet (P?<?0.05). There was a significant interaction between nutritional level and insulin levels at puberty (P?<?0.01). We demonstrated the relationship between IGF-I and average daily gain on the onset of puberty in heifers. In conclusion, heifers submitted to the higher feeding level showed a higher follicular diameter and were younger at puberty.     

The effects of repeated intravenous iohexol administration on renal function in healthy beagles – a preliminary report

Background

Contrast induced nephrotoxicity (CIN) is a well described syndrome in humans undergoing contrast medium examinations. To date CIN has received minimal attention in the veterinary literature despite increasing use of contrast medium examinations in computed tomographic studies.

Methods

This prospective study evaluated the effect of 1290 mg/kg iohexol given intravenously to 5 normal beagle dogs in a divided dose at an interval of 6–8 weeks. Renal function was evaluated by means of scintigraphically determined glomerular filtration rate (GFR) and a variety of laboratory assays.

Results

Only GFR showed a significant decrease (17%) after the second injection but not to a clinically or pathologically significant level.

Conclusions

No clinically significant effect of repeated contrast medium administration was determined in this limited study. However in dogs with reduced renal function the risk of CIN is likely to increase dramatically post contrast administration.