Physiological Predictors in Calves of Dairy Breeds: Part 1. Genetic Parameters of Basal and Induced Growth Hormone Secretion

Abstract

Genetic variation in plasma growth hormone (GH) concentration before and after GRF (growth hormone releasing factor) stimulation was studied in young bulls (N=284) and heifers (N=212), the progeny of 53 sires of four dairy and dual-purpose breeds (Danish Jersey, Red Dane, Danish Friesian and Danish Red and White). Male and female calves were reared, fed and tested on separate experimental stations; thus sex, station and feeding were completely confounded effects. The animals were tested at about 9 months of age, after a 24 h fast. GH concentration was measured in serial plasma samples collected for 1 h before and 1 h following intravenous administration of 2.0 ug synthetic GRF(1–29)NH₂/kg live weight^>0.75. Prior to statistical analysis, concentrations were log_e-transformed. Response variables were BASELINE (mean GH in -15, -5 and 0 min samples) and PEAK (mean GH in 10, 15 and 20 min samples). A statistical model taking at least three generations of ancestral relationships into account was used to estimate variance and covariance components for traits in male and female calves by use of restricted maximum likelihood methods.

Heritability of BASELINE was low (0.04 ± 0.12) in males but high in females (0.60 ± 0.16). The heritability of PEAK was high in both sexes (males, 0.42 ± 0.16; females, 0.60 ± 0.16). Genetic correlations between the same trait measured in males and females were low for BASELINE (r _g = 0.32±0.55) but high for PEAK (r _g = 0.82±0.15). Within sex, BASELINE and PEAK were both highly genetically correlated (males, r _g=0.62 ± 0.40; females, r _g= 1.00 ± 0.07).

We conclude that growth hormone concentration is a highly heritable trait in juvenile cattle of both sexes, and that GRF stimulation is benificial to the uncovering of genetic differences among animals.     

钢筋砼水池软弱地基处理的设计及应用

通过对大型人饮水源工程1500m3水池软弱地基进行换填处理设计,计算换填垫层在不同工况下,砼水池在软弱地基上的承载力和变形。优化必选最佳的组合参数,再强夯处理,结合地基处理技术规范,提出解决中小型砼水池软弱地基的处理方法；结果表明,换填结合强夯法处理软弱地基经济效益良好,满足工程质量和地基承载力要求。      

上海市农民宅基地置换思考与探索——以奉贤区四团镇为例

通过对上海市奉贤区四团镇农民宅基地置换案例的剖析,指出了安置方式单一、宅基地置换资金收支不平衡、置换后农民权益保障不足等问题,给出了探寻多元化安置方式、搭建资金平台、完善后续保障体系等有效的解决方法及途径。     

Effect of delaying the time of insemination with sex-sorted semen on pregnancy rate in Holstein heifers

The objective of the study was to evaluate the interval from onset of oestrus to time of artificial insemination (AI) to obtain the optimum pregnancy rate with sex-sorted semen in Holstein heifers. Heifers in oestrus were detected and inseminated only by using heat–rumination neck collar comprised electronic identification tag at the age of 13–14 months. Heifers (n = 283) were randomly assigned to one of three groups according to the timing of insemination at 12–16 hr (G1, n = 97), at 16.1–20 hr (G2, n = 94) and at 20.1–24 hr (G3, n = 92) after reaching the activity threshold. The mean duration of oestrus was 18.6 ± 0.1 hr, and mean peak activity was found at 7.5 ± 0.1 hr after activity threshold. The mean interval from activity threshold to ovulation was 29.4 ± 0.4 hr. The overall pregnancy per AI (P/AI) was 53.0% at 29–35 days and 50.9% at 60–66 days after AI. There was a significant reduction between G1 (13.8 ± 1.4 hr) and G3 (7.9 ± 1.4 hr) related to the intervals from AI to ovulation time. Sex-sorted semen resulted in significantly higher P/AI at 29–35 days when heifers inseminated in G3 (60.9%) after oestrus than those inseminated in G1 (49.5%) and G2 (48.9%). In terms of fertility, when the temperature–humidity index (THI) was below the threshold value (THI ≤65) at the time of AI, there was a tendency (≤65; 57.2% vs. > 65; 47.1%) for high pregnancy rate. There was no effect of sire on P/AI. In addition, the interaction of the technician with the time of AI was found significant, and three-way interaction of technician, sire and time of AI was tended to be significant on pregnancy rate. Thus, in addition to delaying the time of insemination (between 20.1 and 24 hr) after oestrous detection, THI and experienced technician were also found to be critical factors in increasing fertility with the use of sex-sorted semen in Holstein heifers.     

Intercropping fenugreek (Trigonella foenum‐graecum L.) and barley (Hordeum vulgare L.) with and without biochar: Tests along a competition gradient

Integrating soil amendment biochar to legume‐based intercropping systems may amplify the intercropping benefits and lead to more sustainable production due to its positive effects on the soil physicochemical and biological environment. Fenugreek (Trigonella foenum‐graecum) is a legume used in an intercropping system in several countries in Southern Europe, the Middle East, and Asia. A barley cultivar and an Iranian fenugreek ecotype were studied in two replacement series experiments to find the best combination of the two species as well as the effect of adding biochar to the soil. Fenugreek and barley were grown in 4‐L pots in five density combinations (20:0, 15:5, 10:10, 5:15, 0:20) with and without application of biochar in sandy loam soil. The biomass, nitrogen (N) and carbon (C) amount of the two crops were measured fifty days after sowing, and the Relative Yield Total (RYT) was estimated. Our results showed that biochar application resulted in a higher total biomass, N and C amount in all combinations of fenugreek and barley. Total biomass was increased by biochar 19.2% when fenugreek was grown alone and 8.1 and 12.9% in series with 25 and 50% barley when biochar was added, respectively. Biochar increased dry matter, N and C accumulation in both crop species in the mixtures. An exception was the C amount of barley which was not influenced by biochar in intercropping. RYT values were largest for biomass, C and N amount in mixtures with 15 fenugreek plants per pot and 5 barley plants per pot corresponding to approximately 400 fenugreek plants per m mixed with 130 barley plants per m². Biochar application increased RYT of the total dry weight by 2.7 and 5.5% in mixtures of 25 and 50% barley plants, RYT of the total nitrogen by 0.8% in mixtures with 25% barley plants, and RYT of the total carbon by 2.7 and 6.6% in mixtures with 25 and 50% barley plants. The RYT values declined with increasing number of barley plants as a result of a less competitive ability of fenugreek when growing in high barley densities. The yield was highest with intercropping but monoculture of barley also resulted in high yields. The total highest yield was found when approximately 130 fenugreek plants per m² were mixed with 400 barley plants per m². Mixtures with 75% fenugreek and 25% barley obtained RYT values larger than 1 for biomass, carbon and nitrogen percentages.     

高粱替代不同水平玉米对育肥猪生长性能、胴体性状及肉品质的影响

本试验旨在研究高粱替代不同水平玉米对育肥猪生长性能、胴体性状及肉品质的影响。选择160头体重[(48.93±3.01)kg]相近的健康杜×长×大三元育肥猪,随机分为4组,即对照组(基础饲粮)、30%替代组(用高粱替代基础饲粮中30%的玉米)、65%替代组(用高粱替代基础饲粮中65%的玉米)和100%替代组(用高粱替代基础饲粮中100%的玉米),每组4个重复,每个重复10头猪(5头去势公猪、5头母猪)。试验期60d。结果显示:1)高粱替代不同水平玉米对育肥猪的料重比、平均日采食量无显著影响(P>0.05);与对照组相比,100%替代组平均日增重降低3.4%(P<0.05)。2)与对照组相比,30%替代组、65%替代组和100%替代组背膘厚度分别提高3.0%、5.2%和4.3%(P<0.05)。3)与对照组相比,30%替代组、65%替代组和100%替代组背最长肌pH45min分别提高0.5%、1.0%和0.4%(P<0.05);65%替代组和100%替代组背最长肌中粗脂肪含量分别提高8.7%和11.3%(P<0.05)。4)与对照组相比,100%替代组背最长肌中谷氨酸和苏氨酸含量分别降低2.5%和11.7%(P<0.05)。5)与对照组相比,100%替代组背最长肌中油酸、反式油酸、花生酸和花生四烯酸含量分别提高15.3%、39.6%、56.8%和52.4%(P<0.05);65%替代组背最长肌中反式油酸、花生酸、二十碳三烯酸和花生四烯酸分别提高37.9%、77.15%、72.2%和53.2%(P<0.05)。综上所述,本试验条件下,用高粱替代饲粮中部分玉米不仅对育肥猪的生长性能无负面影响,还能够通过提高肌肉中部分不饱脂肪酸含量而改善肉品质。     

Heat production, eating behavior and milk yield of lactating cows fed two rations differing in roughage content and digestibility under heat load conditions

The objective of this study was to measure the effect of feeding two total mixed rations (TMRs), differing in their roughage content and in vitro dry matter digestibility, on the respiratory rate, body temperature, eating behavior and energy balance of lactating cows. The partitioning of metabolizable energy intake (MEI) between heat production (HP) and retained energy (RE) of cows held under heat load conditions was measured. Forty-two lactating cows were divided into two similar sub-groups, each of 21 animals, and were fed either a control (CON) ration containing 18% roughage neutral detergent fiber (NDF) or an experimental (EXP) TMR that contained 12% roughage NDF and used soy hulls as partial wheat silage replacer. The in vitro DM digestibility of the CON and EXP TMRs was 75.3 and 78.6%, respectively (P < 0.05). The EXP diet reduced rectal temperature and respiratory rate of the cows while increasing their number of meals per day by 32.7% as compared with the CON fed cows, and these meals were shorter in duration and were eaten faster. The EXP diet increased total DM intake from 19.6 to 21.5 kg/cow/d, milk yield from 32.3 to 34.6 kg, and yield of energy corrected milk from 30.9 to 32.2 kg, as compared with the CON group. Cows fed the EXP TMR had increased RE in milk and body tissue, as compared with the CON group, but the diets had no effect on the measured HP that was maintained similar (121 vs. 127 MJ/cow/d) in the two groups. The measured MEI (MEI = RE + HP) and the efficiency of MEI utilization for RE production, were similar in the two dietary groups.     

The traditional inexplicable replacement of seed and seed ware of landraces and cultivars: A review

A review is presented on the often inexplicable seed replacement by farmers. Such a seed replacement has been mentioned since Biblical times and earlier. It occurred and still occurs all over the world and for all cultivated plants. In order to find out whether or not this seed replacement has some meaningful background, farmers in those areas where this type of seed replacement still takes place should be interviewed. Maybe, this seed replacement is based on farmers' experience since times immemorial in which farmers obtained (or believed to obtain) lower yields if seed is not replaced. If so, the cause of this type of seed replacement can be explained. This revised version was published online in August 2006 with corrections to the Cover Date.     

Nitrogen fertilization value of compost and dried dung in soils with contrasting synthetic nitrogen fertilization histories

If the production of forage for dairy cattle is to become less reliant on synthetic nitrogen (N) fertilizers, there is need to better understand and account for the N contributed by on-farm and imported organic amendments. A 254-day aerobic soil incubation study (typical length of a growing season in many temperate dairying regions) quantified the inorganic (mineral) N supply from a commercial compost and dried bovine dung (i.e., on-farm effluent solids). Amendments were incubated in soils with contrasting synthetic N fertilization histories (i.e., 70–100 vs. 350–400 kg N/ha per year) to evaluate if higher synthetic N fertilization histories would reduce the lag time that often exists between organic amendment application and significant release of inorganic N for plant uptake. This proposition was based on previous research, which showed greater soil inorganic N availability accelerating organic amendment decomposition. Our experiment did find that the release of inorganic N from evaluated organic amendments was greater in soils with higher synthetic N fertilization histories, but that this effect was not apparent until after the first 6-months of this 9-month experiment. Despite this finding, soils with contrasting synthetic N fertilization histories were not found to differ in their initial inorganic N content, nor microbial activity or other physiochemical properties known to affect N mineralization. Our study highlighted the long-term vision needed when transitioning from synthetic N fertilizers to organic amendments, with most of the N present in the compost and dried dung remaining unavailable for forage production (i.e., remained bound in organic carbon-based molecules).     

Effects of partial or total replacement of fish meal with freeze‐dried krill (Euphausia superba) on growth and nutrient utilization of juvenile Atlantic cod (Gadus morhua) and Atlantic halibut (Hippoglossus hippoglossus) fed the same practical diets

Studies were conducted with juvenile (28 g) Atlantic cod (Gadus morhua) and halibut (Hippoglossus hippoglossus) fed fish meal (FM) based diets with partial (0%, 25%, 50% and 75%) or total (100%) replacement of FM with freeze‐dried krill (FDK). Addition of dietary FDK significantly stimulated feeding activity in both species and resulted in higher feed consumption and intakes of digestible protein (DP) and energy (DE). This is a significant finding on the feed attractant properties of FDK because it occurred despite having 2–4 MJ kg^?1 higher levels of DE in the FDK diets which could have had an intake suppression effect. In addition, it indicates that the soluble protein fraction of krill thought to be responsible for its attractant properties and is routinely lost or greatly reduced during commercial processing of krill meals, is retained by freeze‐drying. Supplementation of FDK significantly improved growth rates, digestibility and nutrient utilization. Levels exceeding 25–50% FM replacement, however, generally did not significantly increase growth performance or nutrient utilization. In addition, feed formulations with high FDK (>75% replacement) are likely to be cost‐prohibitive as long as the market price remains higher than FM.