Schreurs Nm

Meta-analysis of the effect of animal maturity on muscle characteristics in different muscles, breeds, and sexes of cattle

The effect of animal maturity on fiber cross-sectional area, percentage of fiber types, activities of isocitrate dehydrogenase (ICDH) and lactate dehydrogenase (LDH), total and insoluble collagen and lipid concentration was investigated in the longis-simus thoracis (LT), semitendinosus (ST), and triceps brachii (TB) muscles. The analysis considered 2,642 muscle samples from bulls, steers, and cows of Aubrac, Charolais, Limousin, Montbéliard, and Salers breeds. For the bulls, the fiber cross-sectional area, percentage of slow oxidative fibers, and ICDH activity showed a quadratic relationship (P < 0.05), and the percentage of fast oxidative-glycolytic and fast glycolytic fibers and LDH activity showed a cubic relationship (P < 0.05) with increased maturity. A linear relationship was observed for the collagen and lipid muscle characteristics. The response equation coefficients for different muscles indicate that development of muscle characteristics is different for each muscle. Compared with the other muscles, ST muscle had a greater fiber cross-sectional area, proportion of fast glycolytic fibers, LDH activity, and collagen content. The LT muscle had a greater proportion of slow-oxidative fibers and lipid (P < 0.05). Within the ST muscle, all characteristics except lipid concentration showed different development between the breeds. Steers showed greater changes in muscle fiber cross-sectional area, percentage of fast oxidative-glycolytic and fast glycolytic fibers, and total lipid in the muscle with increasing maturity compared with bulls. The mean fiber cross-sectional area and percentage of fast glycolytic fibers was greater and the mean lipid concentration was less in bulls compared with steers (P < 0.05). Data for cows were from more mature animals. Muscle characteristics in cows did not show large changes with increasing degree of maturity. Muscle type accounts for a greater proportion of the variation in the muscle characteristics than breed and sex of the animal.

The effects of condensed tannins from Dorycnium rectum on skatole and indole ruminal biogenesis for grazing sheep

Skatole and indole are flavour compounds formed in the rumen, which are key factors in the pastoral flavour of meat and milk products. A selection of indolic compounds has been screened for their potential to form skatole and indole on in vitro fermentation, with rumen inocula collected from New Zealand pasture-fed sheep. Typically, 8% (P < 0.005) of added tryptophan was converted to indole and 54% (P < 0.001) was converted to skatole via indole acetic acid (IAA). The addition to rumen inocula of a condensed tannin (CT) fraction isolated from the forage legume, Dorycnium rectum, reduced the conversion of plant protein to skatole and indole by 75% and specifically inhibited the transformation of IAA to skatole by 85% (P < 0.001). The conversion of tryptophan to indole or IAA was not affected by CTs. The inhibitory effect of CTs on the conversion of tryptophan to skatole was prevented by the addition of polyethylene glycol (PEG) to the rumen inocula prior to the addition of CTs, but not by the addition of PEG subsequent to CTs, demonstrating that interactions between CTs and microbes involved in skatole biosynthesis are not reversible by PEG. This study is the first to demonstrate that isolated CTs have an inhibitory effect on the conversion of protein to skatole and indole by rumen microbes, and that CTs specifically inhibit the transformation of IAA to skatole by rumen microbes.

Effects of grazing undrenched weaner deer on chicory or perennial ryegrass/white clover pasture on the viability of gastrointestinal nematodes and lungworms

This study determined the in vitro effects on the viability of internal parasites of grazing undrenched weaner deer on either chicory (Cichorium intybus) or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pasture. One experiment investigated the hatching and development of gastrointestinal nematode eggs and larvae, and the development and motility of Li lungworm (Dictyocaulus eckerti) larvae, and a second experiment used larval migration inhibition assays to test the viability of LI lungworm larvae extracted from the faeces of weaner deer grazed on either chicory or pasture when they were incubated with rumen and abomasal fluids from fistulated deer also grazing on chicory or pasture. The incubations were undertaken with and without added condensed tannins purified from chicory and with or without polyethylene glycol (PEG) to bind the tannins. Chicory had no effect on the hatching and development of gastrointestinal nematode eggs and larvae. Grazing chicory reduced the number of lungworm larvae developing to the L3 stage, and Li lungworm larvae from the faeces of chicory-grazed deer were less viable in rumen and abomasal fluid than larvae from pasture-grazed animals. Abomasal fluid was significantly (P<0.001) less inhibitory to the migration of Li lungworms than rumen fluid. When the larvae were incubated in rumen and abomasal fluids from chicory-grazed deer, their passage through sieves was significantly (P<0.001) reduced in comparison with when they were incubated in the fluids from pasture-razed deer. Adding condensed tannins to rumen fluid increased the inhibition of the migration of Li lungworm larvae but PEG removed this inhibition; this effect was not observed with abomasal fluid.

Balancing consumer and societal requirements for sheep meat production: an Australasian perspective.

Although there has been a decline in sheep numbers in Australia and New Zealand, both countries remain significant producers and exporters of sheep meat. The ongoing demand for more sustainable and ethical animal farming systems and practices requires sheep production industries to be both vigilant and responsive to consumer and the broader societal needs. Demonstration of continuous improvement in animal welfare is paramount and the welfare risks and challenges confronting Australasian sheep industries now and into the future are discussed.

Response of additional ewe lamb liveweight during gestation on birth and weaning weight of offspring and liveweight of the ewe lamb at weaning

Increasing the liveweight of ewe lambs during gestation may have positive effects on lamb birthweight and weaning weight and also on ewe lamb liveweight at weaning. Specific times during the gestation period of the ewe lamb may be more responsive to improved nutrition and increases in liveweight. The objective of this work was to use a meta-analytic approach to investigate the effects of ewe lamb liveweight at mating and during pregnancy on lamb birth and weaning weights, and the ewe lamb’s liveweight at weaning. Increasing ewe lamb liveweight in early gestation and in particular before mating gave the greatest increases in the birth and weaning weight of the lambs, and also of the ewe lamb’s liveweight at weaning compared with increasing liveweight in the second and third trimester of gestation. This indicates that management practices for ewe lambs that generate higher liveweight at mating are likely to result in increased lamb survival, higher weaning percentages, greater lamb weaning weights and create rising 2-year-old ewes with better liveweight for mating in the subsequent season. Compared with ewe lambs that gave birth and reared singletons to weaning, those ewe lambs that gave birth to twins and reared twins had greater increases in lamb birthweights, lamb weaning weights and ewe lamb weights at weaning for each extra kilogram of ewe lamb liveweight during gestation. For ewe lambs, especially those that birth and rear twins, management options that increase the pre-mating weights will have the greatest response in lamb birthweight, weaning weight and liveweight of the ewe lamb itself at weaning.

Effect of birthweight and birth rank on the survival of single and twin lambs born to ewe lambs

Benefits of ewe lamb mating include improved lifetime production, increased rates of genetic gain and higher net profits. These benefits are only achieved if the ewe lamb successfully rears its offspring to weaning. A meta-analytic approach was used to assess the effects of birthweight and the interacting effect of birth rank on the survival to weaning of lambs born to ewe lambs. The data were from eight studies where birthweight and weight at weaning had been recorded for lambs born from ewe lambs. Data were for single- (n = 1392) or twin-born lambs (n = 456). The twin lambs were further classified as the ‘heavier’ or ‘lighter’ of the pair to give three birth rank categories. To compare the probability of dying before weaning between birth ranks, but with lambs compared at a similar birthweight, lambs were categorised by their birthweight as heavy (>3.8 kg) or light (<3.8 kg) and also categorised within their birth rank on their placement around the mean birthweight (birthweight deviation). A mid-range birthweight deviation fell between one standard deviation above or below the mean for each birth rank, whereas a low- and high-range birthweight fell below and above the mid-range, respectively. Logistic regression was used to assess the effect of birth rank (single, heavier twin and lighter twin) and birthweight on lamb mortality up to weaning. To compare the probability of surviving up to weaning between the different birth ranks, relative risk ratios were calculated. Birth ranks were compared for lambs within the same birthweight group (heavy or light) and same birthweight deviation (low-, mid-, high-range). Decreasing birthweight increased mortality before weaning in twins and the change in mortality was greater for the lighter twin. Birthweight did not alter mortality before weaning in singles. Comparison of the birth ranks showed that there were differences (P < 0.05) in the probability of dying for lambs of different birth ranks but similar birthweight. The results suggest that management options for ewe lambs that increase the birthweight of the lighter twin could increase the weaning percentage.

Meta-analysis to establish the response of having heavier mature ewes during gestation on the birthweight of the lamb and the weaning weight of the ewe and lamb

There is much uncertainty about feeding ewes to maximise the performance of progeny and of the ewe itself to weaning. This includes questions about feeding the ewe to influence the lamb’s birthweight for lamb survival, feeding to augment the ewe’s lactation to maximise the lamb’s growth potential before weaning and feeding the ewe to increase the probability of having multiple offspring. The objective of this study was to carry out a meta-analytic study to consider the response of having heavier mature ewes during gestation on lamb and ewe performance measured by birth and weaning weights. The birthweight of singleton lambs was the greatest, twins were intermediate and triplets the lowest (5.8, 4.8 and 4.1 kg, respectively; P < 0.001). A similar trend (P < 0.001) was observed for the weaning weight of the lamb (29.1, 25.2 and 23.7 kg for lambs weaned as a single, twin or triplet, respectively). The liveweight of ewe at weaning was greater (P < 0.001) for those ewes that failed to wean a lamb (69.6 kg) or weaned a single lamb (67.8 kg) compared with ewes that weaned twin and triplet lambs (64.8 and 65.3 kg; respectively). A greater ewe liveweight during gestation gave different responses on the lamb birthweight, lamb weaning weight and the weaning weight of the ewe and this was dependent on birth and weaning rank category of the lamb (P < 0.05). Overall, the response of heavier ewes on lamb birthweights and ewe and lamb weaning weights was small compared with the effect of birth and weaning rank of the lamb.

Carcass characteristics and meat quality of Hereford sired steers born to beef-cross-dairy and Angus breeding cows

Steers from Angus, Angus×Holstein Friesian, Angus×Holstein Friesian-Jersey and Angus×Jersey cows and a Hereford sire were measured for their carcass and meat quality characteristics. Steers from the Angus×Holstein Friesian cows had a greater final body weight and carcass weight (P<0.05). Steers from Angus×Jersey cows had the lowest carcass weight and dressing-out percentage (P<0.05). There was a greater fat depth over the rump at 12 and 18months of age for the steers from Angus cows (P<0.05) but, not at 24months of age. The steers had similar meat quality characteristics across the breed groups. Steers from Angus×Holstein Friesian and Angus×Jersey cows had a higher ratio of n6 to n3 fatty acids. Using beef-cross-dairy cows to produce steers for meat production does not impact on meat quality. Using Jersey in the breed cross reduced the carcass tissues in the live weight and the potential meat yield.

Association between FASN gene polymorphisms ultrasound carcass traits and intramuscular fat in Qinchuan cattle

Fatty acid synthase (FASN) is an enzyme involved with fat deposition and fatty acid composition in cattle. This study was conducted to detect single nucleotide polymorphisms (SNPs) of the FASN gene and explore their relationships with ultrasound carcass traits in order to assess the potential use of the FASN gene for the breeding selection of Qinchuan cattle for desirable carcass traits. The frequencies of SNP g.12740C>T, g.13192T>C and g.13232C>T were identified in 525 individual Qinchuan cattle which were also assessed for backfat depth, eye muscle area and intramuscular fat by ultrasound. According to the PIC values, g.13192T>C possessed an intermediate polymorphism (0.25<PIC<0.5). The SNPs of g.13232C>T, g.12740C>T possessed low polymorphism (PIC<0.25). Chi-square tests showed that g.13192T>C were in Hardy-Weinberg disequilibrium (c2<c0.052). Two SNPs were found to be associated with variation in ultrasound carcass traits. The H2H2 diplotypes had a greater back fat depth than H1H1, H1H4 and H1H2 (P<0.01). The TT genotype at g.13192T>C was associated with a greater eye muscle area and the TT genotype at g.13232C>T was associated with greater intramuscular fat. When these genotypes were combined there was no difference in eye muscle area and intramuscular fat between the diplotypes. The H2H2 diplotype was associated with carcass traits that are likely to provide economic advantage in Qinchuan cattle. Variations in the FASN genes and their corresponding genotypes may be considered as molecular markers for economic traits in cattle breeding.

Dynamic modelling of contractile and metabolic properties of bovine muscle

During bovine growth, a dynamic multifactor process influences the development of muscle characteristics that influence meat quality. This paper fits non-linear equations to data from growing cattle in order to provide a mathematical description of the development of contractile and metabolic muscle characteristics. The muscle characteristics considered were: the mean cross-sectional area of muscle fibres, fibre type proportions and the glycolytic and oxidative enzymatic activities represented by lactate dehydrogenase (LDH, glycolytic) and isocitrate dehydrogenase (ICDH, oxidative). The Gompertz equation was used to describe the increase in fibre cross-sectional area as cattle mature. The proportion of oxidative fibres in the muscle was modelled using a 3-parameter equation to denote an initially fast increase in the proportion of oxidative fibres which then slowed with increased degree of maturity. A 4-parameter equation represented the proportion of glycolytic fibres and LDH activity in the muscle which increased with increasing maturity and then decreased after puberty. An equation was fitted to the data of ICDH activity in the muscle which had an exponential decrease followed by a linear increase with increasing maturity. For each muscle considered, the rate of change in the contractile and metabolic muscle characteristics differed between beef breeds (e.g. Charolais) compared with non-beef breeds (e.g. dual-purpose or dairy breeds) and also between bulls compared to cows and steers. These differences in muscle development were accounted for by fitting different parameters for each breed and sex group. Assessment of the mean square deviation indicated that parameterisation was logical given the biological responses observed from animal experiments.