A productivity model for first thinning of Pinus patula using a tractor and double-drum winch in South Africa

The productivity of skidding tractors in intermediate harvesting operations has not been determined in Mpumalanga, South Africa. The objective of this study was to develop a productivity model using a farm tractor in first thinning operations in Pinus patula compartments. A work study design was used to assess the performance of a skidding agricultural tractor. From 350 samples, important data variables collected were elemental times for each work cycle, extraction distance, slope and load volume. Stepwise and subsets regression analyses were conducted prior to multiple linear regression analysis. Analysis of variance was used to compare mean productivity estimates of the different models developed. Results showed that the best model was estimated by an interaction of distance × slope (ds), distance × load volume (dv) and slope × load volume (sv) as follows: ln(?₂) = 1.33–0.00154ds + 0.00174dv + 0.161sv. The mean estimate for this model was 5.036 m³ m h^?1. The developed models predicted similar results to estimation results of the observed model, although there were statistically significant (P < 0.001) differences among mean estimates (3.6–5.5 m³ m h^?1). All of the three models yielded R²_adj. = 38%; SE = 0.458% at P < 0.001. It can be speculated that the remaining variation not explained by the models may be associated with long extraction distances, delays and the effect of slope as a main variable in the model. While the developed models mirrored reasonably well with the observed estimates of skidding productivity, these models should not be stretched to conditions dissimilar to those of their generation. Future research focus should be made on (1) effects of weather conditions and vehicular characteristics on skidding productivity and (2) the effect of winching lines on skidding productivity.     

Non-clinical intramammary infection in lactating ewes and its association with clinical mastitis

A bacteriological survey for the study of non-clinical intramammary infection in the sheep udder was carried out in 88 Assaf ewes. A mean infection prevalence in the first few weeks of lactation was 55%. The most common bacterial isolates were Micrococcus spp. followed by coagulase negative staphylococcus, together accounting for 93% of the total number of isolates. An infection prevalence of 54% was found in ewelambs 2 days after their first lambing, indicating a marked new infection rate around lambing. Generally, the course of lactation was characterized by dynamic changes of new infection and spontaneous resolution. About 5% of half udders examined developed clinical mastitis. The comparison of bacteriological data from mastitic milk samples and from samples taken from the same half udders before the appearance of the clinical disease could not support the theory that in sheep, mastitis is a clinical exacerbation of a non-clinical intramammary infection.     

Nonsynonymous natural genetic polymorphisms in the bovine leptin gene affect biochemical and biological characteristics of the mature hormone

Leptin (LEP) is a cytokine-like hormone proven to be involved in diverse biological processes. In livestock, it regulates feed intake, BW homeostasis, and energy balance, among other traits. Natural nonsynonymous genetic polymorphisms in the ovine leptin (oLEP) alter the biochemical and physiological characteristics of its gene products. Here we studied in vitro and in vivo the biochemical and physiological characteristics of recombinant hormones representing the oLEP and bovine leptin (bLEP) reference sequences of wild-type (WT) leptins (GenBank accession No. U84247 and U50365, respectively), oLEP and bLEP recombinant muteins carrying the R4C mutation, and oLEP recombinant hormones carrying the A59V and Q62R mutations, which were detected in bLEP. All proteins were purified to homogeneity as monomers and formed 1:1 molar ratio complexes with the chicken leptin-binding domain (LBD). Surface plasmon resonance experiments revealed that all protein variants exhibit reduced (P < 0.05) affinity to chicken (ch) and human (h) LBD compared with the WT oLEP and bLEP recombinant proteins. The ovine and bovine R4C muteins exhibited significantly (P < 0.05) greater induction of cell proliferation in a Baf/3 cell line bioassay, despite lower affinity toward both hLBD and chLBD. Intra-third cerebral ventricle infusion of oLEP and its 3 muteins in sheep resulted in reduced feed intake. However, the 3 tested muteins had a decreased (P < 0.05) inhibitory effect than the WT LEP. It was concluded that natural genetic polymorphisms in the bLEP are associated with variation in the biochemical and physiological properties of the protein.     

Plasma concentrations of key metabolites and insulin in late-pregnant ewes carrying 1 to 5 fetuses

Ewes bearing more than 1 fetus are more susceptible to pregnancy toxemia than those with a single fetus. Crossbreeding programs in Israel increased the occurrences of ewes bearing more than 2 fetuses; therefore, the aim was to assess the exacerbation in the metabolic status of ewes pregnant with several fetuses. Fifty ewes, genetically developed to achieve multiple-fetus pregnancies, were monitored, on average, from d 115 of pregnancy until lambing for plasma concentrations of several key metabolites and insulin. The numbers of fetuses were examined by ultrasonography at 35 d of pregnancy. Blood samples were collected weekly, and concentrations of glucose, β-hydroxybutyrate (BHBA), NEFA, triglycerides, cholesterol, total calcium, and insulin were determined. The average litter size was 2.75 (±1.1), and 1 (1F), 2 (2F), 3 (3F), and 4 or more (4F) fetuses were conceived, respectively, by 6 (12%), 17 (34%), 14 (28%), and 13 (26%) ewes. Total birth weights of lambs were 6.1, 9.5, 12.7, and 15.0 kg for 1F, 2F, 3F, and 4F, respectively (P < 0.001). Plasma glucose concentrations in 1F were greater than those in 3F and 4F (P < 0.05) and were similar among 2F, 3F, and 4F. Trends toward increasing plasma concentrations of BHBA and NEFA were observed as the number of fetuses increased and also as lambing approached. Plasma concentrations of BHBA and NEFA were, respectively, 3.7 (P < 0.002) and 2.1 (P < 0.001) times as great in 4F ewes as in 1F ewes. Trends toward decreased concentrations of triglycerides and cholesterol were observed as litter size increased. Insulin concentrations in blood decreased considerably as the numbers of fetuses increased and, on average, they were less by a factor of 5 in the 4F ewes than in the 1F ewes (P < 0.001). Moreover, insulin concentrations during the week before lambing were extremely low (e.g., 0.54 μIU/mL in the 4F ewes). Insulin concentrations were reduced in ewes bearing >3 fetuses, even 5 wk before lambing; this decline apparently began earlier than the last month of gestation. Therefore, it seems that insulin has a pivotal role in the etiology of pregnancy ketonemia in ewes carrying multiple fetuses. The present findings may suggest that the decline in insulin concentrations that apparently occurs in the earlier stages of pregnancy represents a homeorhetic control to spare glucose for the brains and fetoplacental units of the dams. The results clearly demonstrate the increased susceptibility to pregnancy toxemia of ewes carrying multiple fetuses. Appropriate nutritional strategies should be developed for ewes that conceive >3 fetuses, to meet the increased nutritional requirements of the fetoplacental unit.     

Removal of Silver and Lead Ions from Water Wastes Using Azolla filiculoides, an Aquatic Plant, Which Adsorbs and Reduces the Ions into the Corresponding Metallic Nanoparticles Under Microwave Radiation in 5?min

Pollution of water bodies with heavy metal ions is a major worldwide environmental problem. The objective of this study was to elucidate the mechanism in which metallic ions are adsorbed and reduced to metallic nanoparticles onto plant materials using microwave radiation. In this research, we have fabricated metallic silver and lead nanoparticles from their corresponding ions using the aquatic plants Azolla filiculoides and Pistia stratiotes (since identical results are obtained for both plants, the emphasis will be on the Azolla) under microwave radiation. Our data show that metallic silver and metallic lead nanoparticles were completely removed from the polluted solution and were embedded in the A. filiculoides surface after 5 min of microwave reaction. It was also found that, for both metals, reduction of the metallic ions was accomplished by the plant matrix without the need of an external reducing agent. Most of the particles had a spherical shape within the 10?C50 nm size range. Mass balance data clearly indicate that most of the silver particles were found on the surface of the plant and not in the clean water. Pectin and ??-glucuronic acid did not reduce the silver or lead ions under microwave radiation. We therefore hypothesize that perhaps the proteins or sugar alcohols in the plant matrix were serving as the reducing agents. We believe that this technique in which adsorption and reduction are combined using microwave radiation can be applied for removing and recycling metallic ions from contaminated water and industrial wastewater.     

Overexpression of parathion hydrolase in Escherichia coli stimulates the synthesis of outer membrane porin OmpF

Parathion hydrolase (PH), also known as organophosphorus acid anhydrase, hydrolyses the triester linkage found in organophosphates including organophosphate pesticides and the nerve gas sarin. The enzyme is reported to be membrane-associated and the immature protein has a signal sequence of 29 amino acids. In experiments designed to examine the post-translational processing of the enzyme and to assess the distribution of the precursor and mature forms of the protein, we induced expression of the Flavobacterium balustinum PH structural gene, opd, in Escherichia coli strain BL21. Western blotting revealed that the induced PH was predominantly membrane-associated in E. coli but a protein band equivalent in size to mature PH was also found to be induced specifically in periplasmic fractions. This periplasmic protein was not PH, as it did not cross-react in Western blots, and N-terminal sequencing of the induced protein showed it to have 100% homology to the outer membrane protein OmpF.     

Mini review: breeding Awassi and Assaf sheep for diverse management conditions

The Local Awassi, a triple-purpose breed for meat, milk, and carpet–wool production, is a low-prolific, hardy breed that is well adapted to the unfavorable conditions of the Middle East, where it is managed under traditionally extensive to semi-extensive conditions. Breeding work with the Awassi has included within-breed selection, crossbreeding, and gene introgression. Those efforts resulted in a variety of Awassi-derived genotypes that successfully occupy semi-intensive as well as intensive production systems. Thus, within-breed selection resulted in development of the “Improved Awassi”—a dairy-type Awassi strain which, under intensive management, produces over 500 l milk/ewe annually; crossbreeding with the East Friesian breed led to the development of the Assaf dairy breed, which exceeds the Improved Awassi in prolificacy and in year-round breeding activity, and introgression of the B allele of the FecB locus into the Awassi and Assaf breeds resulted in the formation of the prolific Afec Awassi and Afec Assaf strains, with prolificacies of 1.9 and 2.5 lambs born per ewe lambing, respectively. Advanced molecular genetics tools have enabled a better understanding of how the Awassi breed was formed during domestication and have uncovered differences in its genetic structure compared to other breeds. Implementing large-scale selection schemes that implement emerging new information on the sheep genome, overcoming threats of inbreeding depression, and further breeding for high uterine capacity are the new breeding goals for the Awassi, Assaf, and their derivatives.