Temperature gradient gel electrophoresis: detection of a single base substitution in the cattle β-lactoglobulin gene

An A in equilibrium with G transition in exon III is known to differentiate alleles A and B of the cattle beta-lactoglobulin (BLG) gene. A BLG exon III fragment containing the transition site was amplified by the polymerase chain reaction. Temperature gradient gel electrophoresis (TGGE) was then used to detect this transition and hence to genotype cattle: the AT base-pair in allele A was readily distinguished from the GC base-pair of allele B. TGGE can be used to detect any single base-pair substitution, and thus is a powerful method of detecting genetic variability.     

LiGAPS-Beef,a mechanistic model to explore potential and feed-limited beef production 1: model description and illustration

The expected increase in the global demand for livestock products calls for insight in the scope to increase actual production levels across the world. This insight can be obtained by using theoretical concepts of production ecology. These concepts distinguish three production levels for livestock: potential (i.e. theoretical maximum) production, which is defined by genotype and climate only; feed-limited production, which is limited by feed quantity and quality; and actual production. The difference between the potential or limited production and the actual production is the yield gap. The objective of this paper, the first in a series of three, is to present a mechanistic, dynamic model simulating potential and feed-limited production for beef cattle, which can be used to assess yield gaps. A novelty of this model, named LiGAPS-Beef (Livestock simulator for Generic analysis of Animal Production Systems – Beef cattle), is the identification of the defining factors (genotype and climate) and limiting factors (feed quality and available feed quantity) for cattle growth by integrating sub-models on thermoregulation, feed intake and digestion, and energy and protein utilisation. Growth of beef cattle is simulated at the animal and herd level. The model is designed to be applicable to different beef production systems across the world. Main model inputs are breed-specific parameters, daily weather data, information about housing, and data on feed quality and quantity. Main model outputs are live weight gain, feed intake and feed efficiency (FE) at the animal and herd level. Here, the model is presented, and its use is illustrated for Charolais and Brahman × Shorthorn cattle in France and Australia. Potential and feed-limited production were assessed successfully, and we show that FE of herds is highest for breeds most adapted to the local climate conditions. LiGAPS-Beef also identified the factors that define and limit growth and production of cattle. Hence, we argue the model has scope to be used as a tool for the assessment and analysis of yield gaps in beef production systems.     

Winter feeding systems and dairy cow breed have an impact on milk composition and flavour of two Protected Designation of Origin French cheeses

This study investigates the effects of two feeding systems and two dairy cow breeds on milk yield and composition, physical and sensorial properties of Camembert and Pont-l’Evêque cheeses. The experiment consisted of a 2 × 2 factorial arrangement of treatments. A low energy grass diet with only 15% of concentrate (LowGS) was compared with a high-energy maize silage diet with 30% concentrate (HighMS). Thirty-four Holstein (Ho) and 34 Normande (No) cows in early lactation were assigned to one of two feeding systems for a 6-week period. Cows on the LowGS feeding system had lower milk yield, fat and protein content. In both feeding systems, No cows had lower milk yields but higher milk protein contents than Ho cows. The LowGS feeding system altered milk fatty acid (FA) composition by reducing saturated FA. Breed had only a small impact on milk FA. Concerning milk coagulating properties, only the firmness was reduced by the LowGS feeding and the Ho breed. The effects of breed and feeding system on the protein content of cheeses were more marked in Camembert cheese than in Pont-l’Evêque cheese. However, the Camembert cheese from Ho-LowGS was, in fact, characterized especially by lower protein content. LowGS feeding system and No breed produced more yellow cheeses. Feeding systems had limited effects on the firmness of Camembert and Pont-l’Evêque cheeses measured by penetrometry. In sensory analysis, Ho breed and LowGS feeding produced a Camembert cheese with a more melting texture in the mouth due to the increase of spreadability index and of proteolysis. The type of cheese also had an influence: the effects were more important on Camembert cheese than on Pont-l’Evêque cheese. Only the Ho-LowGS treatment produced a very specific Camembert cheese different from the others. The feeding systems and breed of dairy cow have no determinant effect on PDO (protected designation of origin) Camembert and Pont-l’Evêque cheeses, especially regarding taste. In this kind of trial, despite the effects of feeding systems and breed on milk composition, the role of cheese ripening and microbiology appears to be of considerable importance.     

Expected early genetic gain from selection for milk yield in dairy cattle

Summary A matrix program to predict short term genetic gain from single trait selection for milk yield was developed. Rate of genetic gain was calculated as the annual change in the mean breeding value of all producing females. Several parameters sets representing various selection policies were used to examine situations pertinent to dairy populations of the United States. Approach to the asymptotic rates of genetic gain within the model varied with the choice of parameters, but even with consistent selection policies, predicted total genetic gain in the first 10 years was only half of the expected from classical theory. Considerable year to year variation in the rate of gain occurred. Early gains were more dependent on female selection decisions than gains during the steady state. In a two-phase model, the approach to the linear rate of gain in the second phase was accelerated by starting with an ongoing improvement program, but considerable delays still existed. Selection for sex- limited traits such as milk yield, which require pedigree selection and a waiting time for progeny test results reached asymptotic rates more slowly than previously assumed.     

Phenotype frequencies of vitamin D binding protein (Gc) and of posttransferrin-2 (Ptf-2) in Belgian cattle breeds*

The vitamin D binding protein (Gc) and posttransferrin-2 (Ptf-2) phenotypes have been determined in a number of Belgian cattle breeds. A very slow migrating variant of the Gc protein — Gc C — has been found in White and Red East Flemish breed. This variant was absent from the other breeds studied. This slow variant was identified as a vitamin D binding protein by autoradiography. The Gc C protein was shown to be controlled by a codominant autosomal allele Gc C at the Gclocus. The Gc C protein is probably identical with a fraction previously described in buffalo and an Italian cattle breed. The allele frequencies for the Gc and Pft-2 systems are reported for several Belgian breeds of cattle.     

On the bovine F blood group system

The F system of three Danish cattle breeds as determined by four specific anti-sera is described. In the Jersey breed three alleles are recognised. In the Danish cattle breeds there was no indication of a null allele. However, the phenotypes observed in zebu cattle by means of four reagents suggest the presence of at least six alleles in the bovine F system. Furthermore, the data show that the factors V₁ and V₂ do not form a linear subtype system in all cattle breeds.     

Efficacy of winter–spring strategic control against Rhipicephalus (Boophilus) microplus infestations on cattle in an area with ecological conditions highly favourable for the tick in northeast Argentina

This work was performed to test the efficacy of winter–spring control strategies against Rhipicephalus (Boophilus) microplus (Ixodida: Ixodidae) infestations on cattle in the area ecologically most favourable for the development of this tick in Argentina. Two control schemes using three and four annual applications of acaricides, respectively, were evaluated. Animals in Group 1 were treated with ivermectin 3.15% on day 0, fluazuron on day 34, and fipronil on day 85. Animals in Group 2 were treated with ivermectin 3.15% on day 0, fluazuron on day 34, flumethrin on day 85, and fipronil on day 114. Animals in Group 3 represented the control group. Both treatment schemes provided appropriate levels of efficacy against R. microplus and also prevented the occurrence of the major peak in the frequency of this tick in autumn. The two treatment schemes were similar in terms of efficacy and thus the addition of a fourth treatment does not seem to confer any further advantage. The results of this work indicate that these strategic control methods provide appropriate levels of control against R. microplus.     

Horses grazing with cattle have reduced strongyle egg count due to the dilution effect and increased reliance on macrocyclic lactones in mixed farms

Strongyle infection is an important issue in horse breeding. It impairs horse health and performance, with young horses being the most sensitive. Strongyle control has long relied on the systematic use of chemical treatments. However, expanding anthelmintic resistance among strongyles calls for alternative options. Mixed grazing is assumed to reduce strongyle load on the pasture as the result of a dilution effect. This has been shown in small ruminants grazing with cattle, but the putative benefits of co-grazing between horses and cattle have not yet been evaluated. Here, we conducted field surveys and face-to-face interviews on 44 farms from two contrasted saddle-horse production areas, Normandy and northern Massif Central, to compare equine strongyle management practices between specialized systems and mixed horse-cattle systems. Our goals were (i) to quantify breeders’ awareness of the putative benefits associated with the co-grazing of horses and cattle, (ii) to establish whether mixed farming was associated with different strongyle management strategies and (iii) to test whether strongyle egg excretion was reduced in horses grazed with beef cattle. Every breeder relied on systematic calendar treatments, and only 8 out of the 23 mixed breeders were aware that co-grazing of horses with cattle could be used as part of their strongyle control strategy. Management practices were similar across both systems in Normandy. In Massif Central, mixed breeders formed a distinct cluster from their specialized counterparts: deworming was less frequent and stocking density was higher in mixed farms, while specialized breeders seemed more willing to integrate herd and plot management into control strategies. Faecal egg counts measured in horses from Massif Central were significantly reduced when horses were grazed with cattle. This was the result of an increased reliance on macrocyclic lactones in mixed farms (P < 0.01) and a significant dilution effect (P < 0.01). When considering a subsample of horses treated with macrocyclic lactones only, young horses grazed with cattle had 50% fewer strongyle eggs excreted in their faeces than horses grazed in equine-only pastures (P < 0.01). This is the first evidence of the benefits of mixed grazing with cattle as an alternative to control strongyle infection in horses, although this promising alternative remains largely unknown by horse breeders.