The non-linear effect (determined by the penalised partial-likelihood approach) of milk-protein concentration on time to first insemination in Belgian dairy cows

The time to first insemination in dairy cows depends partly on the energy balance of the cow. Because milk-protein concentration is related to the energy balance, we investigated whether milk-protein concentration predicted the hazard of being inseminated. The main objective of the paper is to demonstrate that the relationship between milk-protein concentration and the hazard of being inseminated was not linear and that this non-linear relationship was modelled adequately using cubic–splines. The semiparametric Cox model was used to introduce protein concentration into the model as a time-varying covariate and additionally herd was added to the model as a frailty term to adjust for the clustering of the cows within a herd. We extended the penalised partial-likelihood technique to fit the frailty model with cubic–splines for the effect of the protein concentration. The model was fitted for a large database consisting of 5114 multiparous cows from 181 different farms. Low milk-protein concentration (<2.7%) was associated with a negative energy balance and this probably led to the decreased hazard. On the other hand, high milk-protein concentration (>4.0%) was linked with low milk production and it was probably a farmer’s decision not to inseminate such cows, leading to the observed decreased hazard.     

Short-term effects of energy changes on plasma leptin concentrations and glucose tolerance in healthy ponies

To determine whether plasma leptin concentrations and glucose tolerance are affected by changes in energy balance, nine healthy Shetland ponies were fed at 140% followed by 75% of their maintenance requirements for 13 days in each of the two periods. Bodyweight was recorded every three days. Blood samples were taken every two days and analysed for leptin and cortisol. An oral glucose tolerance test was performed on day 7 of each period. Serial blood samples were analysed for glucose and insulin. Although bodyweight was not affected, plasma leptin concentrations increased (P<0.001) initially during overfeeding, but returned to previous values after 7 days. During underfeeding, plasma leptin concentrations decreased (P<0.001). Underfeeding was associated with a higher AUC for plasma glucose (P=0.02) and plasma insulin (P=0.05) resulting in a decreased glucose tolerance (AUC glucose/AUC insulin; P=0.008), probably due to a plasma cortisol increase caused by the reduced feed intake. It is concluded that changes in energy balance, without altering bodyweight, can influence plasma leptin concentrations in ponies.     

Development of a sanitary risk index for Salmonella seroprevalence in Belgian pig farms

The aim of this study was to develop a scientifically based Sanitary Risk Index (SRI), defined as an objective measure of the Salmonella seroprevalence in a pig herd based on the risk factors being present on the farm. Therefore, an observational epidemiological study was adopted to infer risk factors for the Salmonella seroprevalence of market pigs. A total of 204 Belgian farrow-to-finish pig herds were included in this cross-sectional study. The antibody titre to Salmonella in sera was analysed by means of an enzyme-linked immunosorbent assay (ELISA) for an average of 58 finisher pigs on each farm. A detailed questionnaire, covering an extensive range of potential risk factors was completed by each participating pig producer. Pearson correlation coefficients between the average sample to positive ratio (S/P)-value of a herd and the within-herd proportion of seropositive pigs were high. Significant risk factors associated with the average S/P-value of a herd were identified by a general linear mixed model. Feeding of meal, providing wet feed, having a hygienic-lock facility, using boot baths, applying the strict all in/all out procedure, programming the temperature in the zone of thermal neutrality and disinfecting between batches were all associated with lower average S/P-values. Sampling in summer, using a clean downtime, decreasing floor space per animal as well as increasing herd size were related with higher average S/P-values. The SRI consists of the above-specified risk factors together with their relative weight. Determining the Salmonella risk of a new herd by the SRI is primarily based on the quantification of the farm specific risk factors present and results in an average S/P-value of the herd. The model was validated using a set of conventional farms. In conclusion, the SRI is a useful preliminary screening tool which forms the basis for targeted sampling but cannot replace the serological herd classification with regard to Salmonella prevalence.     

Association between methylation potential and nutrient metabolism throughout the reproductive cycle of sows

DNA methylation is an important epigenetic strategy for embryo development and survival. The one‐carbon metabolism can be disturbed by inadequate provision of dietary methyl donors. Because of the continuous selection for larger litters, it is relevant to explore if highly prolific sows might encounter periods of methyl donor deficiency throughout their reproductive cycles. This study, therefore, assesses the fluctuation(s) in methylation potential (MP) and aims to link possible methyl donor deficiencies to nutrient metabolism. In total, 15 hybrid sows were followed from weaning of the previous reproductive cycle (d‐5) to weaning of the present cycle. Blood samples were taken at d‐5, 0, 21, 42, 63, 84 and d108 of gestation, the day of parturition (d115), two weeks of lactation (d129) and at weaning (d143). Blood plasma samples were analysed for S‐adenosylmethionine (SAM), S‐adenosylhomocysteine (SAH), free methionine, free glycine, acetylcarnitine and 3‐hydroxybutyrylcarnitine. Serum samples were analysed for urea and creatinine. Generally, MP (i.e. ratio SAM:SAH) increased throughout gestation (p = 0.009), but strongly fluctuated in the period around parturition and weaning. From d108 to parturition, absolute plasma levels of SAM (p < 0.001), SAH (p = 0.031) and methionine (p = 0.001) increased. The first two weeks of lactation were characterised by an increase in MP (p = 0.039) due to a remaining high value of SAM and a distinct decrease in SAH (p = 0.008). During the last two weeks of lactation, MP decreased (p = 0.038) due to a decrease in SAM (p < 0.001) and a stable value for SAH. The methylation reactions seem to continue after weaning, a period crucial for the follicular and embryonic development of the subsequent litter. This study thus demonstrates that the methylation status fluctuates substantially throughout a sow's reproductive cycle, and further research is needed to identify the factors affecting methylation status.     

Effect of the 1BL.1RS translocation and of the Glu-B3 variation on fifteen quality tests in a doubled haploid population of wheat (Triticum aestivum L.)

To investigate the impact of 1BL.1RS translocation on protein content, starch quality, dough rheology, RMT volumes and other quality traits, a doubled haploid population was created and sown in a two-year field experiment. Translocated genotypes accumulated more proteins in the endosperm than non-translocated genotypes. Decrease in the gelatinization of starch was associated with the 1BL.1RS translocation. As for rheological parameters, adapted to bread types not requiring high mixing energy, the 1BL.1RS translocation significantly reduced the elasticity, tenacity and strength of the dough compared to allele c of Glu-B3. Tolerance to over-mixing was also significantly lower in translocated DH lines. In contrast to previously published work, the presence of allele Glu-D3 c resulted in significantly higher tenacity, and thus strength, compared with the allele Glu-D3 b in the present DH population. The final baking test performed on the DH lines of the population, combining favourable alleles for dough rheology and high protein content, demonstrated that in some cases lower tenacity induced by the 1BL.1RS translocation or by Glu-B3 b increases the volume of the loaves.     

Management Processes on Two Small-Holder Sprinkler Layouts: A Case Study from Zimbabwe

Management patterns on two sprinkler schemes forsmall-holders are compared. The one overridingdifference is in the layout – soils, crops, climate,altitude, plot size, source of water and hardwarebeing similar or identical. Both schemes are used bysmall-holders to grow vegetables for cash. One layoutallows for individual control over both crop choiceand water application, and requires one group meetingeach month, to set the fee for the payment of theelectricity bill for the pump-set. The other layout,copied from Zimbabwe's large farms, is shown to imposegroup decision making on the choice of crop andvariety, the area to be planted and the planting date,forcing farmers to hold 17 meetings between July 31stand November 23rd. The case study shows the impact ofthe layout of the hardware on the managementprocess.     

Advances in prevention and therapy of neonatal dairy calf diarrhoea: a systematical review with emphasis on colostrum management and fluid therapy

Neonatal calf diarrhoea remains the most common cause of morbidity and mortality in preweaned dairy calves worldwide. This complex disease can be triggered by both infectious and non-infectious causes. The four most important enteropathogens leading to neonatal dairy calf diarrhoea are Escherichia coli, rota- and coronavirus, and Cryptosporidium parvum. Besides treating diarrhoeic neonatal dairy calves, the veterinarian is the most obvious person to advise the dairy farmer on prevention and treatment of this disease. This review deals with prevention and treatment of neonatal dairy calf diarrhoea focusing on the importance of a good colostrum management and a correct fluid therapy.