Production variability in apple crops

The problem of year-to-year variation in English apple crops was studied for the cultivar ‘Cox's Orange Pippin’ by analyzing data collected from similarly-managed commercial blocks of trees. In the period 1971–1975 yields, in each block of trees, moved in the same direction each successive year. In low-average yield years the variation in yield tended to be as extensive as in high-average yield years. Over the period studied, no relationships between climatic factors during the blossoming-period and subsequent yield could be determined. The most important factor linked with low-average yield was found to be above-normal temperatures in the pre-blossom stage.It was postulated that in order for a tree to carry a crop to its full potential, a decisive vernal temperature impulse is needed. If this dormancy break does not occur, because of above-normal temperatures, a full crop cannot be carried, even though subsequent weather conditions are optimum. Yield failures are attributed to some hormonal or other physiological imbalance occurring due to the lack of the normal decisive vernal dormancy break.It was shown that the alternate-year bearing pattern evident in apple crops in the United Kingdom, The Netherlands and Belgium between the years 1971 and 1975 could be explained by this hypothesis.     

Production of the mouse whey acidic protein in transgenic pigs during lactation.

The mouse whey acidic protein (WAP) gene was introduced into the genome of pigs and its expression was analyzed in the mammary gland. Mouse WAP was detected in milk of lactating females from five lines at levels between .5 and 1.5 g/liter, thereby representing as much as 2% of the total milk proteins. The corresponding mRNA was expressed in mammary tissue at levels similar to those of pig beta-lactoglobulin and beta-casein. The pattern of WAP secretion in three pigs over a period of 6 wk was quantitatively similar to that of pig beta-lactoglobulin. From the eight transgenic pigs analyzed, three successfully completed one lactational period, but five pigs stopped lactating a few days after parturition. Our results show that it is possible to produce large quantities of a foreign protein in milk of pigs over a full lactational period. However, expression of WAP can compromise the mammary gland and render it nonfunctional.     

The effect of two different weaning procedures on the growth of pasture-reared Thoroughbred foals in New Zealand

AIM: To identify if there was a significant difference in the average daily liveweight gain (ADG) between Thoroughbred foals weaned using two weaning protocols commonly used in New Zealand.

METHODS: Sixteen Thoroughbred foals were blocked for sex and age, randomly allocated into progressive (187, SD 33 days; three colts, five fillies) or abrupt (182, SD 28 days; four colts, four fillies) weaning groups, and weighed every second day for 2 weeks either side of weaning, then fortnightly from birth to 480 (SD 31) days old. ADG was calculated to examine the short-term (10 days before weaning, 5 and 10 days post weaning) and long-term (0–6 and 6–16 months of age) effect of the two weaning treatments.

RESULTS: ADG was 1.10 (SD 0.091) kg/day before weaning (0–6 months of age) and 0.59 (SD 0.06) kg/day from weaning to 480 (SD 31) days old. At the start of weaning, liveweights of the progressive and abrupt weaning groups were 276.5 (SD 40.3) kg and 257 (SD 15) kg, respectively (p=0.23). For the 5-day period during weaning, irrespective of treatment, there was a significant decrease in ADG of –0.29 (SD 0.49) kg/day and –0.15 (SD 0.30) kg/day for progressive and abrupt weaning, respectively. There was no significant difference in ADG between weaning methods at any measurement period (short or long term) during and after weaning. However, there was large variation between foals in ADG in the 10 days after the weaning process, which may indicate variation in individual foals' responses to being weaned, rather than the weaning treatment.

CONCLUSIONS: Weaning, irrespective of method, was associated with a decrease in ADG in the first week after weaning. The method of weaning had no effect on post-weaning ADG either short term, 10 days after weaning, or long term up to 480 days of age. Practically, it may be more important to consider maturity and liveweight as criteria for weaning foals rather than age alone.     

Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. Conclusions

This paper summarises and presents in context the main findings of an extensive series of studies of early training lasting 13 weeks in which the tissue responses of 2-year-old Thoroughbred horses were assessed using a combination of methods. Negligible clinical injury was detected and thus the study fulfilled the intention of investigating adaptive change rather than injury. Cancellous and cortical bone, some digital tendons, and articular cartilage responded to early training exercise to a greater or lesser degree. Clinical examination and ancillary diagnostic aids currently in veterinary clinical use are not sufficient to detect early abnormalities in metacarpo-phalangeal joint (MCPJ) cartilage found in both trained and untrained horses. Future work should centre on detection of such changes, on the precise registration of training workload, and on the manipulation of the responses of musculoskeletal tissues by careful investigation of the effects of introducing conditioning exercise at a young age.     

Distribution,biology, ecology and control of the psyllid Diaphorina citri Kuwayama,a major pest of citrus: A status report for China

Abstract

The Asiatic citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is a major pest of citrus in China. Its status derives, not from the damage it causes, but from its role as the only known vector in China of huanglongbing, a phloem-limited bacterial disease of international importance. The disease can devastate orchards within a few years of planting. It also poses a major threat to endangered indigenous citrus germplasm in Asia and Australasia. The distribution, biology, ecology and control of the psyllid in China are reviewed in these contexts. Constraints and challenges related to control of the vector in China are discussed.     

Insulin-like growth factor binding proteins initiate cell death and extracellular matrix remodeling in the mammary gland

We have demonstrated that insulin-like growth factor binding protein-5 (IGFBP-5) production by mammary epithelial cells increases dramatically during forced involution of the mammary gland in rats, mice and pigs. We proposed that growth hormone (GH) increases the survival factor IGF-I, whilst prolactin (PRL) enhances the effects of GH by decreasing the concentration of IGFBP-5, which would otherwise inhibit the actions of IGFs. To demonstrate a causal relationship between IGFBP-5 and cell death, we created transgenic mice expressing IGFBP-5, specifically, in the mammary gland. DNA content in the mammary glands of transgenic mice was decreased as early as day 10 of pregnancy. Mammary cell number and milk synthesis were both decreased by approximately 50% during the first 10 days of lactation. The concentrations of the pro-apoptotic molecule caspase-3 was increased in transgenic animals whilst the concentrations of two pro-survival molecules Bcl-2 and Bcl-x were both decreased. In order to examine whether IGFBP-5 acts by inhibiting the survival effect of IGF-I, we examined IGF receptor- and Akt-phoshorylation and showed that both were inhibited. These studies also indicated that the effects of IGFBP-5 could be mediated in part by IGF-independent effects involving potential interactions with components of the extracellular matrix involved in tissue remodeling, such as components of the plasminogen system, and the matrix metallo-proteinases (MMPs). Mammary development was normalised in transgenic mice by R3-IGF-I, an analogue of IGF-I which binds weakly to IGFBPs, although milk production was only partially restored. In contrast, treatment with prolactin was able to inhibit early involutionary processes in normal mice but was unable to prevent this in mice over-expressing IGFBP-5, although it was able to inhibit activation of MMPs. Thus, IGFBP-5 can simultaneously inhibit IGF action and activate the plasminogen system thereby coordinating cell death and tissue remodeling processes. The ability to separate these properties, using mutant IGFBPs, is currently under investigation.     

The effects of “holding” on some blood parameters in goats

One young male and five female goats aged from four months to mature fullmouthed were handled by stroking and raising the jugular vein intermittently for one minute each day for four days. A control group was kept in a similar pen out of sight of the test group for the four days and approached only when attended for pen cleaning and feeding. On the fifth day, heparinised blood samples were taken once hourly for a period of three hours by jugular venepuncture from both groups. After processing, the samples were examined for packed cell volumes, plasma and erythrocyte potassium and sodium concentrations. Analysis of variance of the data showed a significant (P<0.01) reduction in erythrocyte potassium concentration in the unhandled group (76.3 mmol/l to 74.2 mmol/l) from Time 0 to Time 1, and a similarly significant increase in levels in the handled group (73.7 mmol/l to 78.0 mmol/l) from Time 0 to Time 1. There was also a significant difference (P<0.05) in packed cell volumes between the unhandled and handled groups at Time 0 and Time 1 (28.6% v 25.2% and 27.6% v 25.0% respectively). There were no significant differences between the two groups in plasma sodium, plasma potassium or erythrocyte sodium.