Metabolic and anatomical adaptations of light‐bodied chicks to intermittent feeding

1. Chicks of a light‐bodied strain were deprived of food on alternate days from 15 to 46 d of age.

2. Hyperphagia, amounting to twice the intake of control birds early in the experiment, occurred on the repletion day.

3. Final body weight attained 80% of that of the controls.

4. Body fat concentration decreased at first but returned to that of controls after 3 weeks.

5. A consistent hyperlipaemia was observed after food deprivation or restoration.

6. There was a marked increase in the digestive enzymes found in the small intestine, but not in the pancreas during the repletion day.

7. These responses may be considered as mechanisms to reduce the physiological manifestations of starvation.     

The effect of 6‐ and 8‐hour light‐dark cycles on egg production and pattern of ovipositions

1. Two flocks of 60 laying hens were transferred from 14 h light (L): 10 h dark (D), to repeated 3L:3Dor4L:4D lighting schedules at 37 weeks of age. Egg production decreased slightly but egg weight and shell quality improved.

2. The intake of low‐calcium diet and of oyster shell were similar for each light period of each lighting regimen.

3. Ovipositions were distributed virtually at random throughout the day and the mean interval between successive eggs within a clutch was increased.

4. Reducing the total daily photoperiod from 12 to 6 h decreased daily food consumption.     

Growth and laying performance of light‐hybrid pullets subjected to quantitative food restriction

1. Three degrees of quantitative food restriction producing body weights 88, 76 or 64% of controls at 20 weeks and three times of starting restriction 3, 6 or 9 weeks of age were compared with ad libitum‐fed pullets in a factorial experiment with 1800 light‐hybrid hens. Restrictions were applied such that the target weights were produced irrespective of time of starting.

2. Food intake was least when restrictions were started at 3 weeks.

3. Sexual maturity was delayed in proportion to the severity of restriction and resulted in lower percentages of small eggs.

4. Egg numbers decreased as restriction increased.

5. Mortality in restricted groups during rearing and laying was higher.

6. Optimal restriction was apparently intermediate between treatments producing 88 or 76% of ad libitum‐fed body weight. Body weight was so excessively affected by the most severe restriction that total production was adversely affected.

7. Restriction from 3 weeks was more profitable than restriction from 6 or 9 weeks, resulting in lower food cost during rearing and higher total egg production.     

Battery gage shape: The laying performance of medium‐ and light‐body weight strains of hens

1. One thousand two hundred and ninety‐six medium‐ and 1296 lightweight hens were housed, four to a cage, in deep (conventional) cages, 405 mm wide by 460 mm deep, or shallow cages, 610 mm wide by 305 mm deep, between 18 and 70 weeks of age. The performance of the hens during different periods of the laying stage and over the full laying year was measured.

2. Egg number per medium‐weight hen housed in shallow cages was significantly higher than of hens housed in deep cages between 18 and 30 weeks and 31 and 42 weeks. Thereafter significant differences were not found. With the light‐weight hens the increase was significant only in the 18‐ to 30‐week period. Apart from the 19‐ to 30‐week period hens of both strains housed in shallow cages consumed significantly less food than those in deep cages, the reduction over the full year being about 4%. In all periods the hens housed in the shallow cages converted food more efficiently. Gage shape had no significant effect on mortality.

3. The incidence of hair‐cracked, cracked and broken eggs between 60 and 70 weeks of age from hens housed in shallow cages was lower than that from hens housed in the deep cages but only with the light‐weight hens did this difference reach significance. Shell thickness, shell weight and albumen quality of eggs laid by hens housed in the different shaped cages were not significantly different.     

Adaptation of light‐bodied chicks to meal feeding: Gastrointestinal tract and pancreatic enzymes

1. Two‐week old male chicks of a light‐bodied strain were either fed ad libitum or given one (1M) or two (2M) 2‐h meals per day. A fourth group was pair‐fed (P1M) the amount of food which had been consumed by the 1M group on the preceding day.

2. Compared with ad libitum‐fed counterparts, a marked increase in the relative weight of the storage organs (crop and gizzard) was observed in the meal‐fed birds. The relative weight of the intestine was not affected by meal feeding but the ileal wall became thinner.

3. After food deprivation for 14 or 22 h, respectively, for the ad libitum and the meal‐fed chicks, the weights of contents in the gastrointestinal tract (GIT) segments did not differ between treatments except for those of the gizzard and caecum. Food restoration resulted in an increase in the contents of the GIT of meal‐fed chicks. The increments in the crop and gizzard contents were related to the severity of food restriction. The contents of the intestinal segments were quite similar in all treatments.

4. The activities of the digestive enzymes in the pancreas, expressed as units/g pancreas or units/kg body weight, were not significantly affected by feeding regime. In the small intestine of the meal‐fed birds, marked increases in specific (units/g content) and relative (units/kg body weight) activities were observed of amylase and chymo‐trypsin when compared with their ad libitum‐fed counterparts. The effect of meal feeding on trypsin activities was less pronounced.     

Performance of layers reared and/or kept under different 6‐hour light‐dark cycles

1. Using 60 hens reared and kept on a standard lighting programme (decreasing followed by increasing photoperiod to 22 weeks of age and 14 h continuous light: 10 h continuous dark during lay) as control, the effects of the following intermittent patterns on development and performance were studied. Group 1. The same rearing programme, followed by, between 20 and 36 weeks, 3 h light (L) :3 h dark (D) intermittent and then from 36 weeks a regime in which each light period was progressively shortened by 30 min every 8 weeks with corresponding lengthening of the dark period so that the last cycle used between 52 and 60 weeks was 1.5 h L :4.5 h D. Group 2.6‐hour light‐dark cycles from hatching; the light: dark ratio first decreasing and then increasing, such that total light hours per day varied as in the control group to 20 weeks, and then subsequent lighting as in 1. Group 3. Intermittent lighting of 1.5 h L :4.5 h D unvaryingly from 4 to 60 weeks.

2. Sexual development was essentially the same in all groups. Egg numbers were decreased slightly by the short light‐dark cycles but daily egg mass output was the same in all groups. Food utilisation was best in group 1 and worst in the control group.

3. In general egg weight and shell quality were improved by the short light‐dark cycles; the effect appearing with the first eggs and being especially marked for group 3.

4. On intermittent regimes ovipositions were equally distributed between the four daily light‐dark periods when the light :dark ratio was near unity but were more numerous during the first half of the solar day when the ratio was 1.5 L:4.5 D.     

Differential response of sex‐linked albino (s al ) and silver (S) hens to high and low light intensity

1. Sex‐linked albino (s ^al ) and S (Silver) female chicks were hatched from heterozygous sires from a brown egg‐type line. They were raised in a windowless house and at 17 weeks of age were caged individually in 4 rooms with white fluorescent tubes: two rooms had a “low” light intensity (less than 10 lux) and two had a “high” intensity (average near 400 lux). In total, 157 females completed the experiment.

2. Body weight, sexual maturity, egg weight, the number of abnormal and cracked eggs, efficiency of food utilisation and mortality were not affected either by lighting treatment or by genotype.

3. The genotype X treatment interaction was highly significant for egg number, laying percentage and clutch length to 362 d. The S females were not affected by light intensity. Albino hens of “high” light intensity were superior to the other 3 groups, laying 12 per cent more eggs than non‐albino hens; but their egg production was moderately depressed by “dim” light relative to others.     

Effect of light,vitamin d and dietary phosphorus on egg‐shell quality late in the pullet laying year

1. Eighteen diets supplying all combinations of three phosphorus contents (3.1, 4.0 and 4.8 g non‐phytate P/kg) and six vitamin D supplements (37.5 or 150 μg cholecalciferol/kg; or 16 or 24 μg 25‐hydroxy‐cholecalciferol/kg; or 37.5 μg cholecalciferol/kg with either 16 or 24 μg 25‐hydroxycholecalciferol/kg) were fed to 2 880 pullets of two stocks from 64 to 74 weeks of age. The birds were housed in eight light‐proof rooms, four of which had 24‐h light‐dark cycles (16L : 8D) and four had 28‐h cycles (20L : 8D).

2. The dietary treatments had no significant effect upon food intake, egg output, shell thickness, shell deformation or specific gravity of the eggs.

3. The 28‐h cycle reduced mean rate of lay by 4.5%, increased egg weight by 5.8% and increased shell thickness by 9.4%. The proportion of eggs with shell faults revealed on candling was reduced from 4.1 % to 2.8%.

4. It is concluded from this and other sources that decreasing dietary phosphorus or modifying vitamin D supplements may sometimes lead to increases in shell thickness of the order of 1 to 2%, but that these changes are unlikely to result in a measurable reduction in the proportion of cracked eggs late in the laying year.

5. A 28‐h light‐dark cycle results in a longer and more uniform interval between consecutive ovipositions and thus gives reliable increases in shell thickness which are large enough to reduce the proportion of cracked eggs in many practical situations. Whether it is profitable to use an ahemeral cycle will depend upon the relative prices paid for eggs of different sizes.     

The photoperiodic effect of ahemeral light‐dark cycles which entrain circadian rhythms

1. A 27‐h cycle of light and dark provides a greater gonadotrophic stimulus to the laying fowl, as judged by sexual maturity and rate of lay, than a 24‐h cycle incorporating the same photoperiod.

2. An hypothesis put forward to account for these effects states that Effective Photoperiod equals p + c – b, where p = actual photoperiod, c = cycle length and b = the period of the endogenous biological clock.

3. Two experiments designed to test this hypothesis have yielded results which are consistent with it.

4. A poultryman who uses an ahemeral cycle to alter egg weight or shell thickness and then wishes to transfer his flock back to a 24‐h cycle should calculate the difference between the two cycle lengths and then add this quantity to the prevailing photoperiod to find the appropriate amount of light to be used in the 24‐h cycle.     

Prolonged latency of pupillary light reflex in confined sows: Possible stress-related symptom?

This study aimed to compare pupillary light reflex (PLR) of stall-housed sows with group-housed sows because PLR is a sensitive indicator reflecting psychological state in humans and animals. Six hundred thirty-seven pregnant sows confined in gestation stalls were examined and PLR times (PLRTs) were measured. The results of the chi-square test showed that no significant difference was found in the pupils with PLRT ≥10 seconds between the left and the right pupils (χ2 = 0.03, P > 0.05), and the right-sided pupils with PLRT ≥10 seconds was significantly correlated to left-sided ones (χ2 = 181.85, P < 0.01). Among the 637 individuals, only 38 individuals were found whose PLRT showed >10 seconds on both pupils, accounting for 5.5% of the total. With the treatment of 0.125% of pilocarpine, neither 64 pupils with PLRT ≥10 seconds on the left nor 66 pupils with PRT ≥10 seconds on the right showed sensitivity to pilocarpine. The results also showed that the confined sows had longer PLRT than that of the grouped sows on both the left (13.97 ± 2.96 vs. 8.15 ± 0.97, P < 0.001) and the right (14.01 ± 2.87 vs. 8.19 ± 0.82, P < 0.001) pupils. However, the difference in ratio of the initial pupil size to maximally constricted size was not significant between the 2 groups (P > 0.05). In conclusion, the prolonged latency of PLR or increased PLRT found in the confined sows appeared to be a stressful response to chronic stress. PLRT has the potential to be an indicator used to measure stressed animals.     

How can horseflies be captured by solar panels? A new concept of tabanid traps using light polarization and electricity produced by photovoltaics

Horseflies (Diptera: Tabanidae) can cause severe problems for humans and livestock because of the continuous annoyance performed and the diseases vectored by the haematophagous females. Therefore, effective horsefly traps are in large demand, especially for stock-breeders. To catch horseflies, several kinds of traps have been developed, many of them attracting these insects visually with the aid of a black ball. The recently discovered positive polarotaxis (attraction to horizontally polarized light) in several horsefly species can be used to design traps that capture female and male horseflies. The aim of this work is to present the concept of such a trap based on two novel principles: (1) the visual target of the trap is a horizontal solar panel (photovoltaics) attracting polarotactic horseflies by means of the highly and horizontally polarized light reflected from the photovoltaic surface. (2) The horseflies trying to touch or land on the photovoltaic trap surface are perished by the mechanical hit of a wire rotated quickly with an electromotor supplied by the photovoltaics-produced electricity. Thus, the photovoltaics is bifunctional: its horizontally polarized reflected light signal attracts water-seeking, polarotactic horseflies, and it produces the electricity necessary to rotate the wire. We describe here the concept and design of this new horsefly trap, the effectiveness of which was demonstrated in field experiments. The advantages and disadvantages of the trap are discussed. Using imaging polarimetry, we measured the reflection-polarization characteristics of the photovoltaic trap surface demonstrating the optical reason for the polarotactic attractiveness to horseflies.     

Dose dependent disposition of sulphadimidine and of its N4‐acetyl and hydroxy metabolites in plasma and milk of dairy cows

Summary

The disposition of sulphadimidine (SDM) and of its N₄‐acetyl (N₄‐SDM) and two hydroxyl metabolites, 6‐hydroxymethyl‐ (SCH₂OH) and 5‐hydroxyasulphadimidine (SOH), was studied in plasma and milk of dairy cows following intramuscular or intravenous administration of sulphadimididine‐33.3% at doses of 10, 45, 50, and 100 mg/kg. The main metabolite in plasma as well as in milk was SCH₂OH. The metabolite percentages, the final plasma elimination half‐lives, and the time of peak SDM concentrations in milk are presented for different dosages. The concentrations of SDM and its metabolites in milk ran parallel to those in plasma beyond4 hours p.i. The metabolite concentrations in plasma and milk were lower than those of the parent SDM. Sulphate and glucuronide metabolites could not be detected in milk.

At high doses (45 mg/kg or more) and SDM plasma concentrations exceeding 20 μg/ml, a capacity limited metabolism of SDM to SCH₂OH was noticed, viz, asteady state concentration of SCH₂OH and a biphasic elimination pattern for SDM and SCH,OH in plasma and milk.

The mean ultrafiltrate ratios of the milk to plasma concentrations with respect to SDM, SCH₂OH, SOH, and N₄‐SDM were: 0.69, 0.22, 020, and 0.63, respectively.

The total amount of SDM and its metabolites recovered from the milk after milking twice daily over the whole experimental time was less than 2% of the applied dose.

A bioassay method allowed of detecting qualitatively SDM concentrations exceeding 0.2 μg/ml in plasma or milk. Withholding times for edible tissues and milk are suggested.     

Effect of β -glucanase and xylanase supplementation of barley- and rye-based diets on caecal microbiota of broiler chickens

1. The aim was to investigate the effect of grain type (barley or rye) and exogenous enzymes (β-glucanase or xylanase) on the composition of chicken caecal microbiota as examined by classical culturing and molecular techniques (fluorescent in-situ hybridisation (FISH) and terminal-restriction fragment-length polymorphism (T-RFLP)). 2. Plate counting revealed higher total numbers of anaerobic bacteria, lactic acid bacteria and yeasts in caecal contents of birds fed with rye-based diets than in birds fed with barley-based diets. 3. As assessed by FISH analysis, the most abundant bacterial groups in the broiler caeca were Clostridium coccoides-Eubacterium rectale followed by Bacteroides sp., Lactobacillus sp./Enterococcus sp., Bifidobacterium sp. and Enterobacteriaceae. For both cereal types, the enzyme supplementation significantly decreased the relative amount of Enterobacteriaceae. 4. The T-RFLP profiles indicated that the caecal microbiota of birds receiving rye-based diets was more diverse than that of birds fed on barley-based diets. 5. Irrespective of the method applied, the results indicate that the cereal type as well as the exogenous enzyme supplementation influence the microbiota in broiler chicken caeca, and may have the effect of reducing potentially pathogenic Enterobacteriaceae populations.     

Comparison and Correlation of Agronomic Characteristics and Fermentation Quality of Different Types of Hybrid Corn北大核心CSCD

In order to select the silage corn (Zea mays L.) hybrids suitable for planting in the northern part of Shanxi Province, the agronomic characteristics of 16 hybrid corn and the fermentation quality of silage prepared after castration were measured. The results showed that in agronomic characteristics, DJJ 26 had the highest plant height and ear height, but its stem diameter was the thinner. The green-leaf number ranked in the top three is TY168, QS 30 and GK516. For yields, DF26 had the highest yield. For ensiling characteristics, except for DH679, TY511, all hybrids were below 4. 20 for pH values. The significantly positive correlation was found between fresh grass yield and stem diameter, green-leaf number, stem weight, ear weight, leaf weight. The Lactic acid content of whole plant corn silage was positively correlated with green-leaf number. Therefore, the corn hybrids with thick stems, more green leaves and good panicle traits should be selected for silage use. The JD65 and TY168, GK516 and QS30 have good growth and fermentation performance, thereby, could be selected for silage corn in the northern part of Shanxi Province. © 2019 China Agricultural University. All rights reserved.     

Effects of altitude and variety on nutrient levels and epiphytes of oats北大核心CSCD

Oat crops are a major animal feed source in the Qinghai-Tibetan plateau and nearby areas. Typically，the crops are used for making silage rather than hay because of frequent rain at harvest in autumn. However，there is little data on how the yield，forage quality and levels of epiphytes that may affect silage quality of different oat varieties are affected by altitude. Therefore，four oat varieties（Longyan No. 3，Longyan No. 5，Baiyan No. 2 and Bayou No. 3） were planted in 8 localities forming an altitude gradient： Huangzhong （2295 m），Tianzhu （2797 m），Shandan （2860 m），Hezuo （2957 m），Haiyan （3052 m），Maqu （3474 m），Maqin （3765 m）and Chengduo （4217 m）. Measurements included crop yield and dry matter （DM），water soluble carbohydrate （WSC），crude protein （CP），neutral detergent fiber （NDF）and acid detergent fiber （ADF）contents，and counts of lactic acid bacteria （LAB），molds，yeasts and aerobic bacteria. It was found that there were significant altitude and variety effects on fresh yield，nutritional quality and microbial epiphyte counts. With increase in altitude，fresh yield，WSC，NDF and LAB counts increased（P<0.05），as much as 284. 00%，15. 49%，10.81% and 11.60% increment were observed at Chengduo site than that at Huangzhong，respectively；meanwhile DM，CP and yeast and mold counts were reduced by 15. 67%，36.27%，23.53% and 7.75% at Chengduo compared with Huangzhong site，respectively. Among the four tested varieties，Longyan No. 5 had the highest fresh yield （75605 kg·ha−1），WSC （201.4 g·kg-1 DM） and NDF （604. 2 g·kg-1 DM） at the Chengduo site，followed by Longyan No. 3. The highest CP （119.7 g· kg-1 DM） and mold counts （4.12 lg cfu·g-1 FM） were observed in Baiyan No. 2 at the Huangzhong site. Bayou No. 3 produced the highest LAB and yeast counts at Maqin and Chengduo sites. In general，Longyan No. 3 and Longyan No. 5 gave better performance at sites above 3000 m altitude；for sites below 3000 m，the four tested varieties were all found to be suitable for silage production. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Prevalence and incidence of Newcastle disease and prevalence of Avian Influenza infection of scavenging village chickens in Timor-Lesté

A longitudinal study to monitor prevalence and incidence of antibodies against Newcastle disease (ND) virus and prevalence of antibodies against Avian Influenza (AI) virus in scavenging village chickens was conducted in 20 villages within 4 districts of Timor-Lesté. A total of 3600 blood samples was collected from 1674 individual birds in 300 household chicken flocks during three sampling periods (December 2008-February 2009, March-May 2009, and June-August 2009). The mean interval between household visits was 101.6±1.9 days. None of the birds enrolled in the study was vaccinated against ND or AI. A haemagglutination inhibition (HI) test was used to determine antibody titres against ND virus and a competitive ELISA and HI tests were used to detect antibody against AI virus. The bird-level ND seroprevalence pooled across all samplings (adjusted for clustering by households) was 4.4% (95% CI 3.5-5.2). The bird-level ND seroprevalence in each of the three sampling periods (adjusted for clustering by household) was 3.0% (95% CI 2.0-4.0), 6.6% (95% CI 5.1-8.0) and 3.6 (95% CI 2.5-4.6), respectively. A total of 12.6% individual birds tested ND seropositive at least once over the total study period (95% CI 10.5-14.7). The flock-level ND seroprevalence (at least one bird tested had antibodies against ND virus) pooled across all samplings was 15.9% (95% CI 13.5-18.3). A total of 35.3% flocks had a minimum of one bird being ND seropositive at least once over the study period. The bird-level incidence rate for the period between the first and the second sampling and between the second and the third sampling was 5.6 (95% CI 4.1-7.5) and 0.5 (95% CI 0.5-3.8) per 10,000 bird-years-at-risk, respectively. A total of 1134 serum samples from the last sampling period between June and August 2009 was tested for antibodies against AI virus. Only 4 samples tested Influenza A positive, indicating a bird-level seroprevalence level for Influenza A of 0.4% (CI 0.0-0.7%). These Influenza A positive samples were further tested for HI antibodies against AI virus subtypes of H5N1, H5N3, H7N3 and H9N2, but all tested negative, suggesting that the influenza antibodies in those four birds resulted from exposure to low pathogenic AI viruses of different H subtypes. Our results indicate that village chickens in Timor-Lesté are exposed to ND virus; there was a higher risk of infection during the early months of 2009 than either immediately prior or subsequent to this. No evidence of infection of village chickens with H5, H7 or H9 AI viruses was detected in this study.     

Production benefits of the crossbreeding of indigenous and non-indigenous ducks—growing and laying period body weight and production performance

To evaluate different crosses and purebreds ducks in respect to various economic traits and to estimate different crossbreeding genetic parameters, a 3?×?3 complete diallel cross involving indigenous duck (DD), Khaki Campbell (KK) and White Pekin (WW) were used to produce three purebreds (DD, KK, WW) three crossbreds (DK, DW, KW) and three reciprocals (KD, WD, WK). A total of 609 ducklings produced were reared on deep litter and the females (316 in number) were evaluated for growing and laying period body weight along with the production performance traits. Different crossbreeding genetic parameters were estimated for different traits. All the traits in respect to body weight gain during growing and laying period and different production traits including laying house mortality rate showed significant (p?≤?0.05) difference between different genetic groups. In general, crossbreds perform better than the purebreds for most of the traits studied. General combining ability (GCA), specific combining ability (SCA) and reciprocal effect (RE) were significant (p?≤?0.01) for body weight and production traits. Egg weight showed significant (p?≤?0.01) difference in respect to GCA, SCA and RE for all the ages of measurement except RE for 30th week egg weight. Laying period mortality rate was only significant (p?≤?0.05) for SCA. Most of the crossbreds recorded heterosis rate in desirable direction for majority of the traits. Overall results revealed that the crossbreds perform well in respect to different traits than the purebreds and may be used to take advantage of heterosis. DW performs well in respect to majority of the traits measured and is of importance for commercial exploitation. Further, pure line selection with development of specialised sire and dam line followed by crossing may be of importance to enhance the performances in the crosses.     

Growth and Development of The Kunlun Type of Wild Yak

The observation of body height and weight of 10 captured wild yak shows the body height and weight of the wild yak at three and four months old were similar with that of domestic yak. At their 24 months old, the body height and weight were higher by 26.9 % and 62.5 % than that of the domestic ones. The results indicate that, once adapted to the half-shed and half-grazing conditions, the tamed Kunlun type of wild yak with superior genetics would grow and develop faster than the domestic yak at elder ages.