The Journal of Agricultural Science - Latest issue

The temporal change in soil organic carbon (SOC) was analysed over an 80-year period based on climate change predictions of four regional circulation models under the International Panel on Climate Change (IPCC) A1B emission scenario in the 21st century. A 20-year (1991–2010) set of observed climate data was used to form the baseline, and generate synthetic data for future scenario analyses. With increasing carbon dioxide (CO2) levels, and under continuous winter wheat production with conventional tillage at different nitrogen (N) input rates, three crop-soil models were used to study the temporal changes of SOC. Results indicated that soil carbon (C) generally decreased over the simulation period. In addition, increased N losses through leaching and denitrification were estimated. Decline in soil C under continuous mono-cropping systems indicated increased focus on N fertilization strategies. The results also suggested significant interactive effect of N input rate and climate variables on soil C and denitrification in response to climate change. The uncertainty was addressed by including the crop-soil models in a mixed-effect analysis so that the contribution of the models to the total variance of random variation was quantified. Statistical analysis showed that the crop-soil models are the main source for uncertainty in analysing soil C and N responses to climate change.

Grain production potential is mainly influenced by agroclimate and land use. In the present study, substantial regional differences associated with the impact of climate change were found (i.e. the degree of climate-related impacts varied among regions). Currently, there is an urgent need for effective responses and adaptations to different agricultural districts and agricultural production modes. Therefore, the aim was to examine ecotones and explore trends and influential factors associated with grain production potential change. Using the Global Agro-ecological Zone model, the grain production potential of West Jilin, China under different conditions during various years were estimated, considering meteorological, soil, topographic, land use and other data. The results showed that total grain production potential (TGrPP) of West Jilin increased continuously from 1976 to 2013. The average annual increase in TGrPP was higher in period 1 (1976–2000) than period 2 (2000–2013). In period 1, grain production potential was influenced mainly by irrigation percentage changes, followed by land use change. The conversion of grassland to farmland was the most important land use change factor that was associated with increased grain production potential. Climate change affected grain production potential in period 1 negatively. In period 2, climate change had the largest impact and land use imparted the smallest effect on grain production potential. Finally, the decrease in irrigation percentage resulted in reduced grain production potential.

Linseed is enjoying renewed popularity worldwide thanks to emerging market opportunities for raw material derived from seeds and stems. The dual-purpose cultivation is particularly attractive to growers for its capacity to yield both seed/oil and straw/fibre; however, field-based research is necessary to identify suitable cultivars to meet modern production goals. Under these premises, a 3-year experimental campaign was conducted to evaluate 18 linseed cultivars potentially interesting for dual-purpose cultivation in Northern Italy. Cultivar performance was evaluated in terms of seed, straw and fibre yield, oil composition and stem fibre content. Inter-annual weather variability explained the largest portion of the total variance. However, the ‘cultivar × year’ interaction was not significant except for seed oil content and composition. Stability analysis showed that at least half of the cultivars were unstable for oil content and α-linolenic acid fraction. A Structural Equation Model was developed to investigate causal relationships between the productive performance and factors such as environmental variables, phenological traits, plant size and density. Rainfall was beneficial to seed yield, both before and after flowering, whereas higher post-flowering air temperature had a depressive effect. A higher oil content was favoured by pre-flowering rainfall. Plant height was negatively associated with seed yield and oil content, but it was positively associated with straw and fibre yield. Plant density was critical for fibre yield since below 500 plants/m2 the increased plant branching makes it difficult to extract fibre. Together with plant density, plant height could be used to manipulate the seed/straw ratio according to production goals.

The current study evaluated the effect of sowing date (early, mid-August or timely, mid-September) on two winter wheat (Triticum aestivum L.) cultivars (Hereford, Mariboss) with different rates of nitrogen (N) (0–225 kg total N/ha) applied as animal manure (AM; cattle slurry) or mineral fertilizers (N: phosphorus: potassium; NPK). Overwinter plant N uptake and soil mineral N content were determined during 2014/15, while harvest yields (grain, straw, N content) were determined during 2014/15 and 2015/16. Overwinter uptake of N was 14 kg N/ha higher in early than in timely-sown wheat. Despite very different yield levels in 2015 and 2016 harvests, the advantage of early sowing on grain yields was similar (1.1 and 0.9 t/ha); straw yield benefits were greater in 2015 (1.7 t/ha more) than in 2016 (0.4 t/ha more). In 2015 and 2016, N offtake was 35 and 17 kg N/ha higher in early than in timely-sown wheat, respectively. The mineral N fertilizer value of cattle slurry averaged 50%. Early sowing increased the apparent N recovery (ANR) for wheat regardless of nutrient source. However, ANR was substantially higher for NPK (82% in 2015; 52% in 2016) than for AM (39% in 2015; 27% in 2016). Performance of the two cultivars did not differ consistently with respect to the effect of early sowing on crop yield, N concentration and offtake, or ANR. Within the north-west European climatic region, moving the sowing time of winter wheat from mid-September to mid-August provides a significant yield and N offtake benefit.

Sustainable ruminant production systems depend on the ability of livestock to utilize increased quantities of grazed herbage. The current study aimed to compare the effect of white clover (WC) inclusion and perennial ryegrass (PRG) ploidy on herbage dry matter (DM) production, plant morphology, nutritive value and biological nitrogen (N) fixation (BNF) under high N fertilizer use (250 kg N/ha) and high stocking rates (2.75 livestock units/ha). Four sward treatments (diploid-only, tetraploid-only, diploid-WC, tetraploid-WC) were evaluated over a full grazing season at a farmlet scale. White clover inclusion had a significant effect on herbage DM production, herbage growth rate, tiller density, organic matter digestibility, crude protein and BNF. Tetraploid swards had a lower tiller density, lower sward WC content and post-grazing sward height and increased organic matter digestibility and crude protein than diploid swards. White clover inclusion improved herbage DM production and nutritive value across a full grazing season, with tetraploid and diploid swards producing similar herbage DM yields across the year. Perennial ryegrass ploidy had an effect on WC morphology as plants in diploid-WC swards had narrower, longer stolons, fewer branches and more petioles than tetraploid-WC swards. The current study highlights the benefit of including WC in grass-based systems under a high N fertilizer regime and high stocking rate.

The present study was aimed at stimulating the growth and yield of Sri Lankan tea cultivar TRI 2025 grown in different climatic regions in the country. The model was developed and calibrated using weather, crop and soil data collected from different climatic zones. The model is designed to simulate shoot replacement cycle, leaf area of a shoot, shoot growth, dry matter partitioning and tea shoot yield. The model was validated using shoot development and growth data not used for model calibration. These validation data were collected from low, mid and high elevations representing temperature and rainfall gradients in the country. Model calibration showed that thermal time required to initiate the fish leaf, 1st, 2nd and 3rd normal leaf in a tea shoot from the time of natural senescence of the scale leaves were 129, 188, 235, 296 °C days, respectively, and a tea shoot reached the harvestable stage after 393 °C days. The model simulated leaf area (cm2) and fresh weight (g/m2) of tea shoots at different developmental stages and locations which were in good agreement with the measured values at the validation stage (R2 > 0.92 and 0.98, respectively). Similarly, simulated shoot yields (g/m2/month) at the validation stage were strongly correlated with the measured values (n = 12, R2 > 0.58, RMSE = 5–17 g/m2/month). Thus, the model can be used to estimate the shoot yield of tea cultivar TRI 2025 grown in different climatic conditions in Sri Lanka. Areas requiring further improvements to the model are also discussed.

Nitrification potential of a tropical vertisol saturated with water was estimated during sequential reduction of nitrate (NO3−), ferric iron (Fe3+), sulphate (SO42−) and carbon dioxide (CO2) in terminal electron-accepting processes (TEAPs). In general, the TEAPs enhanced potential nitrification rate (PNR) of the soil. Nitrification was highest at Fe3+ reduction followed by SO42− reduction, NO3− reduction and lowest in unreduced control soil. Predicted PNR correlated significantly with the observed PNR. Electron donor Fe2+ stimulated PNR, while S2− inhibited it significantly. Terminal-restriction fragment length polymorphism targeting the amoA gene of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) highlighted population dynamics during the sequential reduction of terminal electron acceptors. Only the relative abundance of AOA varied significantly during the course of soil reduction. Relative abundance of AOB correlated with NO3− and Fe2+. Linear regression models predicted PNR from the values of NO3−, Fe2+ and relative abundance of AOA. Principal component analysis of PNR during different reducing conditions explained 72.90% variance by PC1 and 19.52% variance by PC2. Results revealed that AOA might have a significant role in nitrification during reducing conditions in the tropical flooded ecosystem of a vertisol.

Declining pulse production has caused wide concern in recent years. A field experiment was conducted to investigate effects of balance fertilizers based on soil test values and targeted yield equations on soil biological activities, soil quality, nutrient acquisition and grain yield of lentil. Treatments included the use of farmyard manure (FYM), bio-inoculants and inorganic fertilizers at different rates and combinations. The results revealed significant improvement in nodulation, microbial counts, microbial biomass carbon (MBC), soil respiration, soil enzymes and soil organic carbon (SOC) with integrated approaches (i.e. fertilizer plus FYM or bio-inoculants); these improvements led to achievement of the specific target yield of 1.50 t/ha. Although the highest yield was achieved with fertilizers applied for a target yield of 2.0 t/ha, there was significant decline in nodulation, microbial counts, MBC, soil respiration, soil enzymes, SOC and soil quality. Correlation between soil quality index (SQI) and grain yield suggested a significant influence of balanced fertilization based on soil tests and target yield. Principal component analysis revealed the average contribution of soil quality indicators towards SQI was in descending order of SOC > acid phosphatase activity > total culturable fungi > available phosphorus > BMC, which are crucial for sustainable lentil production in alluvial soils.

Rice has the lowest grain protein content (GPC) among cereals. Efforts have been made to improve GPC through the modified bulk-pedigree method of selection. A total of 1780 F8 recombinant lines were derived in the year 2013 from five different cross combinations involving two high-GPC landraces, namely ARC10075 and ARC10063, three high-yielding parents, namely Swarna, Naveen and IR64, and one parent, namely Sharbati, known for superior grain quality with high micronutrient content. Near-infrared spectroscopy was used to facilitate high-throughput selection for GPC. Significant selection differential, response to selection and non-significant differences between the predicted and observed response to selection for GPC and protein yield indicated the effectiveness of this selection process. This resulted in lines with high GPC, protein yield and desirable levels of amylose content. Further, based on high mean and stability for GPC and protein yield over the environments in the wet seasons of 2013, 2014 and the dry season of 2014, 12 elite lines were identified. Higher accumulation of glutelin fraction and non-significant change in prolamin/glutelin ratio in the grain suggested safe guarding of the nutritional value of rice grain protein of most of these identified lines. Since rice is the staple food of millions, the output of breeding for high GPC could have a significant role in alleviating protein malnutrition, especially in the developing world.

The objective of the current experiment was to determine the effects of high-concentration phytase (5000 FTU/kg) feeding to diverse lines of chickens fed phosphorus (P) adequate maize–soybean meal diets (4.5 g/kg non-phytate P) on the performance and intestinal immune function. Performance was measured for outbred broiler (Ross 308) and inbred Fayoumi lines over 0–21 days, and duodenum and ileum were harvested for the determination of mucin-2, interleukin (IL)-1β and IgA mRNA by quantitative reverse transcription polymerase chain reaction. Over the 0–7-day period, there was a significant line × diet interaction, as high phytase supplementation increased broiler average daily gain (ADG), but had no effect on Fayoumi ADG. Treatment of diets with phytase increased expression of the mucin-2 gene in the duodenum mucosa. There were significant interactions between line and age, and line, diet and age on duodenal expression of the IL-1β gene as phytase supplementation of the broiler line reduced IL-1β in comparison to control fed broilers without change in the Fayoumi line. Overall, the addition of a high concentration of phytase to broilers fed adequate concentrations of non-phytate P resulted in improved growth performance early with a reduction in this effect over time. Mucosal mucin-2 expression was increased with high-concentration phytase feeding across both lines, but IL-1β mRNA expression was reduced in the duodenum of broilers fed high concentrations of phytase, suggesting that the increased performance noted might be related to decreased inflammation.

Performance of female Holstein calves (n = 60) were evaluated in three step-down milk feeding programmes: step-down 1 (STP1: 7.5 litres/day milk from days 1 to 21, 6 litres/day milk from days 22 to 42, 4 litres/day milk from days 43 to 63 and 2 litres/day milk from days 64 to 84 of the study); step-down 2 (STP2; 7.5 litres/day milk from days 1 to 21, 6 litres/day milk from days 22 to 42 and 2 litres/day milk from days 43 to 63 of the study); and step-down 3 (STP3; 7.5 litres/day milk from days 1 to 21, 4 litres/day milk from days 22 to 42 and 2 litres/day milk from days 43 to 63 of the study). Intakes of starter were monitored daily and body weight (BW), average daily gain (ADG) and wither height (WH) were measured monthly. Calves in STP3 had lower dry matter intake between 22 and 42 days than STP2 animals, but starter intake was greater in STP2 and STP3 calves than those in the STP1 treatment between 43–63 and 64–84 days. Total ADG was greater in STP2 and STP3 animals than in STP1 calves. No effect of treatment was observed on breeding age, BW, WH or service per conception. In addition, conception rate at first breeding was not influenced by treatment. It was concluded that the STP2 and STP3 milk feeding regimes improved performance in calves and there was no benefit in feeding milk for longer than 63 days in terms of breeding outcomes.

The present study evaluated the effects of isovalerate supplementation on the development of the small intestinal mucosa in dairy calves. Forty-eight Chinese Holstein bull calves at 15 days of age and 45.1 ± 0.36 kg of body weight were assigned randomly to four groups. The treatments were control, low-isovalerate, moderate-isovalerate and high-isovalerate with 0, 3, 6 and 9 g isovalerate per calf per day, respectively. The study comprised 75 days with a 15-day adaptation period followed by a 60-day sampling period. Calves were weaned at 60 days of age. Six calves were chosen from each treatment at random and slaughtered at 30 and 90 days of age. The small intestine morphology and activities of amylase and trypsin improved significantly with increasing age. No interaction between treatments and age was observed. The small intestine length, mucosa layer thickness, villus height and crypt depth increased linearly with increasing isovalerate supplementation. However, the ratio of villus height to crypt depth was not affected by treatment. Activities of amylase and trypsin increased linearly. The lactase activity increased linearly during the 75-day period and for pre-weaned calves but was unaltered for post-weaned calves. The relative mRNA expressions of growth hormone receptor, insulin-like growth factor-1 receptor and sodium-glucose co-transporter-1 in the small intestine mucosa increased linearly, and a similar pattern was observed for the expression of peptide transporter-1 in the duodenum and proximal jejunum. The results suggested that small intestine development was promoted by isovalerate in a dose-dependent manner.

In the present study, precise, animal-based biometric data on the space needed for the body dimensions of individual pigs (static space) were collected. Per batch, two groups of eight piglets each were formed after weaning (35 days old). Using three-dimensional cameras that recorded a piglets’ pen from above and newly developed software, the static space of individuals was determined over 6 weeks. The area covered by an individual increased almost linearly with increasing body weight (R2 = 0.97). At the end of rearing (25 kg body weight), an individual covered 1704 cm2 in standing position, 1687 cm2 in sitting posture and 1798 cm2 in a recumbent position. According to the allometric equation: Space = k × body weight0.667, k values for the static space in standing position (k = 0.021), in recumbent position in general (k = 0.022) and in lateral recumbent posture (k = 0.027) were calculated. Compared with spatial requirements in different countries, the results of static space obtained in the present study revealed that pigs weighing 25 kg are provided with 0.09–0.18 m2 free space per pig which is not covered by the pig's body. This free space can be used as dynamic space needed for body movements or social interactions. The present study was not intended to enhance space recommendations in pig farming, but to demonstrate the amount of free space in a pigs’ pen. It was shown that innovative technologies based on image analysis offer completely new possibilities to assess spatial requirements for pigs.

The present study aimed to evaluate growth performance and meat quality of broiler chicken with respect to feeding of 100 g flaxseed meal (FM)/kg and increasing lysine levels in the broiler diet. The results revealed no effect of lysine and FM feeding on growth performance except for a negative effect of FM on feed efficiency of birds, which was countered by feeding 1.25 BIS lysine. Feeding FM improved the fatty acid profile of broiler chicken meat significantly, whereas no effect was observed for increasing lysine levels beyond BIS recommendation. FM significantly reduced meat cholesterol, fat, water-holding capacity (WHC), extract release volume (ERV) and antioxidant potential, whereas it increased the pH of fresh meat, drip loss and lipid peroxidation of broiler chicken meat. As compared with other lysine levels, generally 1.25 BIS lysine significantly increased the pH of refrigerated stored meat, WHC, ERV and antioxidant potential, whereas it significantly reduced cholesterol, fat, drip loss and lipid peroxidation of broiler chicken meat. Thus, the inclusion of 100 g FM/kg diet along with 1.25 BIS lysine in broiler ration was optimum for desirable broiler performance, fatty acid profile, oxidative stability and other functional properties of broiler chicken meat.