Identification of polymorphisms influencing feed intake and efficiency in beef cattle

Feed efficiency is an economically important trait in beef cattle. Net feed efficiency, measured as residual feed intake (RFI), is the difference between actual feed intake and the predicted feed intake required for maintenance and gain of the animal. SNPs that show associations with RFI may be useful quantitative trait nucleotides for marker-assisted selection. This study identified associations between SNPs underlying five RFI QTL on five bovine chromosomes (BTA2, 5, 10, 20 and 29) with measures of dry matter intake (DMI), RFI and feed conversion ratio (FCR) in beef cattle. Six SNPs were found to have effects on RFI (P < 0.05). The largest single SNP allele substitution effect for RFI was -0.25 kg/day located on BTA2. The combined effects of the SNPs found significant in this experiment explained 6.9% of the phenotypic variation of RFI. Not all the RFI SNPs showed associations with DMI and FCR even though these traits are highly correlated with RFI (r = 0.77 and r = 0.62 respectively). This shows that these SNPs may be affecting the underlying biological mechanisms of feed efficiency beyond feed intake control and weight gain efficiency. These SNPs can be used in marker-assisted selection but first it will be important to verify these effects in independent populations of cattle.     

Genetic parameters for fatty acid composition and feed efficiency traits in Japanese Black cattle

We estimated the genetic parameters related to feed intake (FI), feed efficiency traits (including feed conversion ratio (FCR) and residual feed intake (RFI) of digestible crude protein (DCP) and total digestible nutrients (TDN)), beef marbling score (BMS), melting point of fat (MP) and fatty acid composition. Fat and meat (Musculus trapezius) samples were taken from the carcasses of 863 Japanese Black steers derived from 65 sires, for determination of the MP and fatty acid composition of the total lipid in intramuscular adipose tissue. Genetic parameters were estimated using uni- and bivariate animal models. In addition, pedigree information for 4841 animals was used. Heritability estimates for BMS, MP, individual fatty acids, monounsaturated fatty acids (MUFA), the ratio of saturated fatty acids to MUFA (MUS) and the ratio of elongation (ELONG) were generally high. The FI values of TDN and DCP were also high, but FCRs and RFIs of those were low (0.09 to 0.22). Genetic correlation of BMS with MP was -0.34 (favorable) and with C18:1, MUFA, MUS and ELONG values were 0.40, 0.28, 0.29 and 0.37, respectively (favorable). Genetic correlations of MP with C18:1, MUFA, MUS and ELONG were negative (also favorable) and high (-0.85, -0.98, -1.00 (-0.996) and -0.66, respectively). The correlation estimates for feed efficiency traits of DCP were quite similar to those of TDN. Genetic correlations of BMS with FCRs and RFIs of TDN and DCP were all positive (unfavorable; 0.21 to 0.51), and in particular, the correlations with RFIs of those were high. The correlations of C18:1, MUFA, MUS and ELONG with RFIs of TDN and DCP were positive (unfavorable) but low (0.06 to 0.17), whereas the corresponding correlations with FCRs of those were all negative (favorable; -0.38 to -0.10). These results suggest that the quantity and quality of beef fat can be simultaneously improved and that the quality of beef fat (fatty acid composition) can be improved directly or indirectly with MP. Furthermore, selecting MP or fatty acid traits does not significantly affect feed efficiency.     

The repeatability of feed intake and feed efficiency in beef cattle offered high-concentrate,grass silage and pasture-based diets

Breeding values for feed intake and feed efficiency in beef cattle are generally derived indoors on high-concentrate (HC) diets. Within temperate regions of north-western Europe, however, the majority of a growing beef animal’s lifetime dietary intake comes from grazed grass and grass silage. Using 97 growing beef cattle, the objective of the current study was to assess the repeatability of both feed intake and feed efficiency across 3 successive dietary test periods comprising grass silage plus concentrates (S+C), grazed grass (GRZ) and a HC diet. Individual DM intake (DMI), DMI/kg BW and feed efficiency-related parameters, residual feed intake (RFI) and gain to feed ratio (G : F) were assessed. There was a significant correlation for DMI between the S+C and GRZ periods (r = 0.32; P < 0.01) as well as between the S+C and HC periods (r = 0.41; P < 0.001), whereas there was no association for DMI between the GRZ and HC periods. There was a significant correlation for DMI/kg BW between the S+C and GRZ periods (r = 0.33; P < 0.01) and between the S+C and HC periods (r = 0.40; P < 0.001), but there was no association for the trait between the GRZ and HC periods. There was a significant correlation for RFI between the S+C and GRZ periods (r = 0.25; P < 0.05) as well as between S+C and HC periods (r = 0.25; P < 0.05), whereas there was no association for RFI between the GRZ and HC periods. Gain to feed ratio was not correlated between any of the test periods. A secondary aspect of the study demonstrated that traits recorded in the GRZ period relating to grazing bite rate, the number of daily grazing bouts and ruminating bouts were associated with DMI (r = 0.28 to 0.42; P < 0.05 - 0.001), DMI/kg BW (r = 0.36 to 0.45; P < 0.01 - 0.001) and RFI (r = 0.31 to 0.42; P < 0.05 - 0.001). Additionally, the number of ruminating boli produced per day and per ruminating bout were associated with G : F (r = 0.28 and 0.26, respectively; P < 0.05). Results from this study demonstrate that evaluating animals for both feed intake and feed efficiency indoors on HC diets may not reflect their phenotypic performance when consuming conserved forage-based diets indoors or when grazing pasture.     

A meta-analysis of nutrient intake,feed efficiency and performance in cattle grazing on tropical grasslands

It is essential to quantify the potential of tropical grasslands to allow significant feed efficiency for grazing livestock in controlled conditions such as at pasture. We conducted a quantitative analysis of published studies reporting the experimental results of average daily gains (ADG) and diet characteristics obtained specifically under grazing conditions (17 publications and 41 experiments), which have been less studied compared with controlled conditions in stalls. The database was analyzed to determine the average and range of values obtained for ADG (g/kg BW), dry matter digestibility, intake (DMI) and digestible DMI (DDMI, g/kg BW) and feed conversion efficiencies (FCE), as well as to predict the response of these parameters to the main strategies investigated in the literature – that is, mainly the stocking rate (SR) and the concentrate intake (CI). The ADG reached 1.2 kg BW per day and was directly linked to DDMI (ADG=−1.63+0.42 DDMI −0.0084 DDMI², n=90, r.m.s.e=0.584, R²=0.93). The DDMI, which was representative of the nutrient input, was driven mainly by DMI rather than dry matter digestibility, whereas these two parameters did not correlate (r=0.068, P=0.56). The average global FCE (0.11 g ADG/g DDMI) showed a greater association with the metabolic FCE (0.17 g ADG/g DMI) than the digestive FCE (0.62). The CI (g DM/kg BW) increased ADG (ADG=2376+CI 56.1, n=16, r.m.s.e.=441, R²=0.95). The SR expressed as kg BW/ha decreased the individual ADG by 1.19 g/kg BW per additional ton of BW/ha, whereas the global ADG calculated per ha increased by 0.57 per additional ton BW/ha. When the SR was expressed as kg BW/ton DM and per ha rather than as kg BW/ha, the impact on the individual ADG decreased by 0.18 or 0.86 g per additional ton BW/ha, depending on the initial BW of the cattle. These results provide a better view of the potential performance and feeding of cattle in tropical grasslands. The results provide an improved quantification of the relationships between diet and performance, as well as the overall quantitative impact of SR and supplementation.     

Impact of including growth,carcass and feed efficiency traits in the breeding goal for combined milk and beef production systems

Improving feed efficiency in dairy cattle could result in more profitable and environmentally sustainable dairy production through lowering feed costs and emissions from dairy farming. In addition, beef production based on dairy herds generates fewer greenhouse gas emissions per unit of meat output than beef production from suckler cow systems. Different scenarios were used to assess the profitability of adding traits, excluded from the current selection index for Finnish Ayrshire, to the breeding goal for combined dairy and beef production systems. The additional breeding goal traits were growth traits (average daily gain of animals in the fattening and rearing periods), carcass traits (fat covering, fleshiness and dressing percentage), mature live weight (LW) of cows and residual feed intake (RFI) traits. A breeding scheme was modeled for Finnish Ayrshire under the current market situation in Finland using the deterministic simulation software ZPLAN+. With the economic values derived for the current production system, the inclusion of growth and carcass traits, while preventing LW increase generated the highest improvement in the discounted profit of the breeding program (3.7%), followed by the scenario where all additional traits were included simultaneously (5.1%). The use of a selection index that included growth and carcass traits excluding LW, increased the profit (0.8%), but reduced the benefits resulted from breeding for beef traits together with LW. A moderate decrease in the profit of the breeding program was obtained when adding only LW to the breeding goal (−3.1%), whereas, adding only RFI traits to the breeding goal resulted in a minor increase in the profit (1.4%). Including beef traits with LW in the breeding goal showed to be the most potential option to improve the profitability of the combined dairy and beef production systems and would also enable a higher rate of self-sufficiency in beef. When considering feed efficiency related traits, the inclusion of LW traits in the breeding goal that includes growth and carcass traits could be more profitable than the inclusion of RFI, because the marginal costs of measuring LW can be expected to be lower than for RFI and it is readily available for selection. In addition, before RFI can be implemented as a breeding objective, the genetic correlations between RFI and other breeding goal traits estimated for the studied population as well as information on the most suitable indicator traits for RFI are needed to assess more carefully the consequences of selecting for RFI.     

城市绿地生态系统多角度高光谱光化学反射植被指数与光能利用率的关系

光能利用率(LUE)是陆地生态系统总初级生产力(GPP)估算的一个重要参数。LUE的准确估算对于在区域甚至全球尺度上使用LUE模型估算GPP是非常重要的。一个基于通量塔的观测视场与通量观测足迹在时空上相匹配的自动多角度遥感平台为LUE在站点尺度上的准确估算提供了一个好方法。该文基于通量塔涡度相关(EC)和自动多角度高光谱连续观测获取的连续30 min的数据, 在站点空间尺度和0.5 h与日时间尺度上, 探讨了城市绿地生态系统秋季光化学反射植被指数(PRI)与LUE之间的关系。研究发现, 反映植被叶面积和色素变化的植被绿度指数在秋季呈现逐渐下降的趋势, 表征了植被冠层的状态与结构变化, 叶片从绿色逐渐变黄凋落, 植被冠层叶片的叶绿素逐渐减少, 裸露的枝干增多; 用空气温度和代表物候过程的绝对绿度指数(2G_RB)做线性回归分析, 得到回归系数(R²)为0.60 (p < 0.001)。说明在城市绿地生态系统中, 空气温度是决定植被物候过程的主要驱动因素, 随着植被物候变化, 叶片的凋落导致的裸露土壤的增多以及随时间变化的色素含量和其比例的变化将影响PRI和LUE的关系; 采用植被生长模型(logistic曲线), 拟合时间与2G_RB, 得到曲率变化最快的点, 确定为秋季植被落叶期的初日, 即第290天。在0.5 h和日时间尺度上, PRI都可以捕捉LUE的变化。但是日尺度上不同物候期, PRI和LUE的关系发生了急剧的变化。在秋季植被正常生长期, PRI和LUE之间的关系最密切(R² = 0.70, p < 0.001)。当土壤温度大于15 ℃、光合有效辐射(PAR)大于300 μmol·m^-2·s^-1以及饱和水汽压差(VPD)大于700 Pa的情况下, PRI能够更好地预测LUE。基于通 量塔尺度上时空尺度相匹配, 利用半经验的核驱动二向反射分布函数模型得到的高光谱PRI和通量观测得到的LUE在不同环境条件下的关系以及考虑到在植被的不同物候期对PRI和LUE的关系的优化, 将会更加准确地估算城市绿地生态系统的LUE。     

Satellite estimates of productivity and light use efficiency in United States agriculture, 1982–98

Remote sensing of net primary production (NPP) is a critical tool for assessing spatial and temporal patterns of carbon exchange between the atmosphere and biosphere. However, satellite estimates suffer from a lack of large‐scale field data needed for validation, as well as the need to parameterize plant light‐use efficiencies (LUEs). In this study, we estimated cropland NPP with the Carnegie‐Ames‐Stanford‐Approach (CASA), a biogeochemical model driven by satellite observations, and then compared these results with field estimates based on harvest data from United States Department of Agriculture National Agriculture Statistics Service (NASS) county statistics. Observed interannual variations in NPP over a 17‐year period were well modelled by CASA, with exceptions mainly due to occasional difficulties in estimating NPP from harvest yields. The role of environmental stressors in agriculture was investigated by running CASA with and without temperature and moisture down‐regulators, which are used in the model to simulate climate impacts on plant LUE. In most cases, correlations with NASS data were highest with modelled stresses, while the opposite was true for irrigated and temperature resistant crops. Analysis of the spatial variability in computed LUE revealed significantly higher values for corn than for other crops, suggesting a simple parameterization of LUE for future studies based on the fraction of area with corn. Absolute values of LUE were much lower than those reported in field trials, due to uncommonly high yields in most field trials, as well as overestimates of absorbed radiation in CASA attributed to bias from temporal compositing of satellite data. Total NPP for US croplands, excluding Alaska and Hawaii, was estimated as 0.62 Pg C year^?1, representing ～20% of total US NPP, and exhibited a positive trend of 3.7 Tg C year^?2. These results have several implications for large‐scale carbon cycle research that are discussed, and are especially relevant for studies of the role of agriculture in the global carbon balance.     

浙江三大城市群绿色发展效率时空分异及影响机理

提升浙江三大城市群绿色发展效率是浙江加快建成美丽中国先行示范区的重要途径之一.以三大城市群包含的41个县(市)为依托,以2000-2019年县域面板数据为样本,将超效率SBM模型与窗口分析及测度效率相结合,运用空间计量分析方法研究效率的空间分布及区域差异,并借助面板固定效应模型探索效率的差异化影响机理.结果 表明:研究...     

氮素形态处理下水曲柳幼苗养分吸收利用与生长及养分分配与生物量分配的关系

森林土壤中NO-3-N和NH 4-N的比例不平衡,造成森林树木对养分的吸收与利用、生长以及生物量分配格局发生变化。采用沙培技术,以不同NO-3-N和NH 4-N的比例对水曲柳播种苗木进行处理,研究养分吸收利用与生长的关系以及养分分配格局与生物量分配格局的关系。实验结果表明,虽然水曲柳幼苗偏好NO-3-N,但NNUR、NPUR、NUE、PUE、RGR、NAR以及单株总生物量均没有随NO-3-N的比例增加而增加。在8～9月份水曲柳幼苗生长旺盛时期,NNUR和NUE之间以及NPUR和PUE之间的关系显著,而在9～10月份这两组关系不显著。在水曲柳旺盛生长的8～9月份,NUE和PUE对水曲柳幼苗的NAR具有很大的影响,而在生长较弱的9～10月份,这两者对其NAR影响不大。在8～9月份和9～10月份两个时段内,NUE和RGR之间以及PUE和RGR之间的关系非常显著。在8月份和9月份,在不同氮素形态处理下,水曲柳幼苗体内的氮分配格局决定了其生物量的分配格局,而磷分配格局与生物量分配格局无关。     

Intrinsic water use efficiency controls the adaptation to high salinity in a semi-arid adapted plant,henna (Lawsonia inermis L.)

Adaptation to salinity of a semi-arid inhabitant plant, henna, is studied. The salt tolerance mechanisms are evaluated in the belief that gas exchange (water vapor and CO₂) should play a key role on its adaptation to salt stress because of the strong evaporation conditions and soil water deficit in its natural area of distribution. We grow henna plants hydroponically under controlled climate conditions and expose them to control (0 mM NaCl), and two levels of salinity; medium (75 mM NaCl) and high (150 mM NaCl). Relative growth rate (RGR), biomass production, whole plant and leaf structure and ultrastructure adaptation, gas exchange, chlorophyll fluorescence, nutrients location in leaf tissue and its balance in the plant are studied. RGR and total biomass decreased as NaCl concentration increased in the nutrient solution. At 75 mM NaCl root biomass was not affected by salinity and RGR reached similar values to control plants at the end of the experiment. At this salinity level henna plant responded to salinity decreasing shoot to root ratio, increasing leaf specific mass (LSM) and intrinsic water use efficiency (iWUE), and accumulating high concentrations of Na⁺ and Cl⁻ in leaves and root. At 150 mM NaCl growth was severely reduced but plants reached the reproductive phase. At this salinity level, no further decrease in shoot to root ratio or increase in LSM was observed, but plants increased iWUE, maintaining water status and leaf and root Na⁺ and Cl⁻ concentrations were lower than expected. Moreover, plants at 150 mM NaCl reallocated carbon to the root at the expense of the shoot. The effective PSII quantum yield [Y(II)] and the quantum yield of non-regulated energy dissipation [Y(NO)] were recovered over time of exposure to salinity. Overall, iWUE seems to be determinant in the adaptation of henna plant to high salinity level, when morphological adaptation fails.     

Significant relationships among frost tolerance and net photosynthetic rate,water use efficiency and dehydrin accumulation in cold-treated winter oilseed rapes

Five winter oilseed rape cultivars (Benefit, Californium, Cortes, Ladoga, Navajo) were subjected to 30 days of cold treatment (4 °C) to examine the effect of cold on acquired frost tolerance (FT), dehydrin (DHN) content, and photosynthesis-related parameters. The main aim of this study was to determine whether there are relationships between FT (expressed as LT₅₀ values) and the other parameters measured in the cultivars. While the cultivar Benefit accumulated two types of DHNs (D45 and D35), the other cultivars accumulated three additional DHNs (D97, D47, and D37). The similar-sized DHNs (D45 and D47) were the most abundant; the others exhibited significantly lower accumulations. The highest correlations were detected between LT₅₀ and DHN accumulation (r = −0.815), intrinsic water use efficiency (WUEi; r = −0.643), net photosynthetic rate (r = −0.628), stomatal conductance (r = 0.511), and intracellular/intercellular CO₂ concentration (r = 0.505). Those cultivars that exhibited higher Pn rate in cold (and further a significant increase in WUEi) had higher levels of DHNs and also higher FT. No significant correlation was observed between LT₅₀ and E, PRI, or NDVI. Overall, we have shown the selected physiological parameters to be able to distinguish different FT cultivars of winter oilseed rape.     

Effects of dietary β-glucan and rice fermented on growth performance,fatty acids,and Newcastle disease immune response in turkey broilers

Poultry production has been developing in Vietnam with challenges of disease. Thus, feed additive should be investigated not only growth but also health enhancement. Here, we aimed to determine the effects of Saccharomyces cerevisiae-fermented rice (FR) and β-glucan on turkey’s growth performance, carcass characteristics, immune and fatty acid (FA) profiles. A total of 180 turkey chicks aged 1–56 days were randomly assigned to five sextuplicate groups and the birds had ad libitum feed and water access throughout the experiment. The five treatment groups were given the same diet with different proportions of FR and β-glucan. Broilers supplemented with 4% β-glucan and 4% FR presented the highest and second-highest growth performance, respectively. The 4% β-glucan and 4% FR treatments resulted in the highest carcass characteristic values without significantly affecting the breast or thigh meat pH or cooking loss. The 4% β-glucan and 4% FR treatments maximally increased the Newcastle disease (ND) antibody titers at 28, 42 and 56 days, respectively as well as thymus organ index. The foregoing treatments did not significantly affect the blood profiles relative to the control. However, the 4% FR treatment lowered the blood cholesterol levels (p > 0.05). The total FA profiles did not significantly differ among treatments. Nevertheless, both the β-glucan and FR treatments increased the MUFA levels compared to that of the control (p > 0.05). Hence, the dietary administration of 4% β-glucan and FR to turkey broilers could effectively improve their growth performance and immunity.