Short communication: Stall occupancy behavior of Nili Ravi buffaloes (Bubalus bubalis) when first introduced to freestall housing.

The aim of the present study was to assess stall occupancy of Nili Ravi buffaloes when first introduced to freestall housing. Thirty Nili Ravi buffaloes of different parity, weight, and pregnancy status were enrolled from the dairy farm of the University of Veterinary and Animal Sciences, Lahore, Pakistan. All of the enrolled animals had no previous experience with freestalls. The selected buffaloes were introduced to the freestall shed. During an adaptation period of 7 d, all buffaloes had 24 h of free access to lie down in 1 of 3 areas: (1) freestalls, (2) alleys, and (3) an outside open area. After the adaptation period, all buffaloes were housed indoors during nighttime (restricted period) to ensure that only freestalls or alleys were available as lying areas. An observer monitored animals at 0100 h and recorded the number of animals lying in freestalls, in alleys, and in the outside open area. The results indicated that during the adaptation period, herd-level freestall occupancy in buffaloes remained below 10%. During the restricted period, herd-level stall occupancy was 0, 13, 50, and 90% on d 1, 2, 5, and 17, respectively. Buffaloes with parity ≥3 took fewer days (6.6 ± 1.0; mean ± standard error of the mean) to occupy stalls than buffaloes with parity 2, 1, and heifers (13.2 ± 1.5, 16.7 ± 2.1, and 13.5 ± 2.1 d, respectively). Body weight and pregnancy status of buffaloes did not have any effect on stall occupancy. Buffaloes showed adjacent stall occupancy, filling opposite stalls first. The results indicated that older buffaloes occupied freestalls earlier than younger buffaloes. Our findings would help better manage buffaloes in freestall housing.

Genetic diversity in mutated and non-mutated rice varieties.

We studied the genetic variability due to mutation induced by γ-rays (10, 15, and 20 Kr) on various traits of twelve rice genotypes. Mutated and non-mutated seeds were sown in the field between July 2013 and 2014 using a split plot design. Yield and yield-related trait data was recorded, which showed significant (P < 0.05) genotypic and irradiation effects. Gamma radiation exerted non-significant effects on the panicle length of all plants, indicating the uniformity of performance of this character at different radiation levels. The plant height, grains per main panicle, panicle length, 1000-grain weight, grain weight per main panicle, and fertility percentage was minimum in Basmati-198, Basmati-Pak, Shaheen-2000, Super Basmati, Basmati-385, and Super Basmati, respectively, when exposed to radiation at 20 Kr. However, Basmati-370 attained maximum flag leaf area at this level of radiation. Broad sense heritability ranged from 72.0 to 97.7%, indicating the possibility of selection during earlier generations. Phenotypic correlation was positive and significant between grain weight per main panicle with panicle length and flag leaf area. Number of grains per main panicle and genotypic correlation were positive among grain weight per main panicle, panicle length, fertility percentage, 1000-grain weight, and plant height, indicating the effectiveness of these traits in the selection for yield. Phylogenetic analyses revealed a pair-wise similarity ranging from 0.51-0.76 before mutation and 0.39-0.89 after mutation. This study proved that γ-rays at 20 Kr would be most effective in creating genetic variability in the existing germplasm.

Drought-tolerant rice germplasm developed from an Oryza officinalis transformation-competent artificial chromosome clone.

Oryza officinalis has proven to be a natural gene reservoir for the improvement of domesticated rice as it carries many desirable traits; however, the transfer of elite genes to cultivated rice by conventional hybridization has been a challenge for rice breeders. In this study, the conserved sequence of plant stress-related NAC transcription factors was selected as a probe to screen the O. officinalis genomic transformation-competent artificial chromosome library by Southern blot; 11 positive transformation-competent artificial chromosome clones were subsequently detected. By Agrobacterium-mediated transformation, an indica rice variety, Huajingxian 74 (HJX74), was transformed with a TAC clone harboring a NAC gene-positive genomic fragment from O. officinalis. Molecular analysis revealed that the O. officinalis genomic fragment was integrated into the genome of HJX74. The transgenic lines exhibited high tolerance to drought stress. Our results demonstrate that the introduction of stress-related transformation-competent artificial chromosome clones, coupled with a transgenic validation approach, is an effective method of transferring agronomically important genes from O. officinalis to cultivated rice.

Cow- and herd-level risk factors for on-farm mortality in Midwest US dairy herds.

The objectives of this study were to describe on-farm mortality and to investigate cow- and herd-level risk factors associated with on-farm mortality in Midwest US dairy herds using lactation survival analysis. We analyzed a total of approximately 5.9 million DHIA lactation records from 10 Midwest US states from January 2006 to December 2010. The cow-level independent variables used in the models were first test-day milk yield, milk fat percent, milk protein percent, fat-to-protein ratio, milk urea nitrogen, somatic cell score, previous dry period, previous calving interval, stillbirth, calf sex, twinning, calving difficulty, season of calving, parity, and breed. The herd-level variables included herd size, calving interval, somatic cell score, 305-d mature-equivalent milk yield, and herd stillbirth percentage. Descriptive analysis showed that overall cow-level mortality rate was 6.4 per 100 cow-years and it increased from 5.9 in 2006 to 6.8 in 2010. Mortality was the primary reason of leaving the herd (19.4% of total culls) followed by reproduction (14.6%), injuries and other (14.0%), low production (12.3%), and mastitis (10.5%). Risk factor analysis showed that increased hazard for mortality was associated with higher fat-to-protein ratio (>1.6 vs. 1 to 1.6), higher milk fat percent, lower milk protein percent, cows with male calves, cows carrying multiple calves, higher milk urea nitrogen, increasing parity, longer previous calving interval, higher first test-day somatic cell score, increased calving difficulty score, and breed (Holstein vs. others). Decreased hazard for mortality was associated with higher first test-day milk yield, higher milk protein, and shorter dry period. For herd-level factors, increased hazard for mortality was associated with increased herd size, increased percentage of stillbirths, higher somatic cell score, and increased herd calving interval. Cows in herds with higher milk yield had lower mortality hazard. Results of the study indicated that first test-day records, especially those indicative of negative energy balance in cows, could be helpful to identify animals at high risk for mortality. Higher milk yield per cow did not have a negative association with mortality. In addition, the association between herd-level factors and mortality indicated that management quality could be an important factor in lowering on-farm mortality, thereby improving cow welfare.

Identification of neutral genes at pollen sterility loci Sd and Se of cultivated rice (Oryza sativa) with wild rice (O. rufipogon) origin.

Pollen sterility is one of the main hindrances against the utilization of strong intersubspecific (indica-japonica) heterosis in rice. We looked for neutral alleles at known pollen sterility loci Sd and Se that could overcome this pollen sterility characteristic. Taichung 65, a typical japonica cultivar, and its near isogenic lines E7 and E8 for pollen sterility loci Sd and Se were employed as tester lines for crossing with 13 accessions of wild rice (O. rufipogon). Pollen fertility and genotypic segregations of the molecular markers tightly linked with Sd and Se loci were analyzed in the paired F(1)s and F(2) populations. One accession of wild rice (GZW054) had high pollen fertility in the paired F(1)s between Taichung 65 and E7 or E8. Genotypic segregations of the molecular markers tightly linked with Sd and Se loci fit the expected Mendelian ratio (1:2:1), and non-significances were shown among the mean pollen fertilities with the maternal, parental, and heterozygous genotypes of each molecular markers tightly linked with Sd and Se loci. Evidentially, it indicated that the alleles of Sd and Se loci for GZW054 did not interact with those of Taichung 65 and its near isogenic lines, and, thus were identified as neutral alleles Sd(n) and Se(n). These neutral genes could become important germplasm resources for overcoming pollen sterility in indica-japonica hybrids, making utilization of strong heterosis in such hybrids viable.

Genetic analysis of NaCl tolerance in tomato.

We attempted to find the suitable parents for the development of tomato hybrids for high salt soils by exploiting combining ability, gene action and heterosis. Six salt-tolerant and three salt-intolerant genotypes, along with their 18 F1 crosses, were evaluated at seedling stage under 10 and 15 dS/m (NaCl) salinity stress, compared to the control level of salinity. The experiment was laid out based on a two-way complete randomized design factorial arrangement with two replications; data on root and shoot length, fresh and dry weights, leaf area, plant length, Na(+), K(+) and K(+)/Na(+) concentrations were recorded. There was significant variation within genotypes, lines, testers, crosses, and line × tester interaction for all plant characters studied under normal and two salinity levels. Estimates of combining ability indicated that under low (10 dS/m) and high (15 dS/m) salinities, line BL1176 and tester LO2875 showed significant GCA effects for most of the traits studied. The cross-combinations 6233 × LO2875, CLN2498A x LO2875 and BL1176 × 17902 showed highest SCA values for most of the characters under 10 and 15 dS/m, respectively. Potence ratio showed that under low and high salinities, all the traits showed over dominant type of gene action except leaf area and K(+) concentration (in 10 dS/m) and shoot length, and leaf area (in 15 dS/m). The highest heterosis for most of the parameters was observed in cross-combinations BL1176 × LO2875 and CLN2498A x LO2875.

Allelic interaction of F1 pollen sterility loci and abnormal chromosome behaviour caused pollen sterility in intersubspecific autotetraploid rice hybrids.

The intersubspecific hybrids of autotetraploid rice has many features that increase rice yield, but lower seed set is a major hindrance in its utilization. Pollen sterility is one of the most important factors which cause intersubspecific hybrid sterility. The hybrids with greater variation in seed set were used to study how the F(1) pollen sterile loci (S-a, S-b, and S-c) interact with each other and how abnormal chromosome behaviour and allelic interaction of F(1) sterility loci affect pollen fertility and seed set of intersubspecific autotetraploid rice hybrids. The results showed that interaction between pollen sterility loci have significant effects on the pollen fertility of autotetraploid hybrids, and pollen fertility further decreased with an increase in the allelic interaction of F(1) pollen sterility loci. Abnormal ultra-structure and microtubule distribution patterns during pollen mother cell (PMC) meiosis were found in the hybrids with low pollen fertility in interphase and leptotene, suggesting that the effect-time of pollen sterility loci interaction was very early. There were highly significant differences in the number of quadrivalents and bivalents, and in chromosome configuration among all the hybrids, and quadrivalents decreased with an increase in the seed set of autotetraploid hybrids. Many different kinds of chromosomal abnormalities, such as chromosome straggling, chromosome lagging, asynchrony of chromosome disjunction, and tri-fission were found during the various developmental stages of PMC meiosis. All these abnormalities were significantly higher in sterile hybrids than in fertile hybrids, suggesting that pollen sterility gene interactions tend to increase the chromosomal abnormalities which cause the partial abortion of male gametes and leads to the decline in the seed set of the autotetraploid rice hybrids.