Chitosan (CHI) is a natural biopolymer with antimicrobial, anti-inflammatory, antioxidant and digestive modulatory effects, which can be used in the ruminant diet to replace antibiotics. The aim of this study was to evaluate the effects of CHI on lamb growth traits, nutrients digestibility, muscle and fatty deposition, meat fatty acid (FA) profile, meat quality traits and serum metabolome. Thirty 30-month-old male lambs, half Suffolk and half Dorper, with an average BW of 21.65 ± 0.86 kg, were fed in a feedlot system for a total of 70 days. The lambs were separated into two groups according to the diet: the control (CON) group which received the basal diet and the CHI group which received the basal diet with the addition of CHI as 2 g/kg of DM in the diet. Lambs supplemented with CHI had a greater (P < 0.05) final BW, DM intake, final body metabolic weight (P < 0.05) and lower residual feed intake than the CON group. Animals fed CHI had a greater (P < 0.05) starch digestibility at 14 and 28 days, average daily gain at 14, 42 and 56 days, greater feed efficiency at 28 days and feed conversation at 14 and 42 days in feedlot. Most of the carcass traits were not affected (P > 0.05) by the treatment; however, the CHI supplementation improved (P < 0.05) dressing and longissimus muscle area. The treatments had no effect (P > 0.05) on the meat colour and other quality measurements. Meat from the CHI-fed lambs had a greater concentration (P < 0.05) of oleic-cis-9 acid, linoleic acid, linolenic-trans-6 acid, arachidonic acid and eicosapentaenoic acid. According to the variable importance in projection score, the most important metabolites to differentiate between the CON and the CHI group were hippurate, acetate, hypoxanthine, arginine, malonate, creatine, choline, myo-inositol, 2-oxoglutarate, alanine, glycerol, carnosine, histidine, glutamate and 3-hydroxyisobutyrate. Similarly, fold change (FC) analysis highlighted succinate (FC = 1.53), arginine (FC = 1.51), hippurate (FC = 0.68), myo-inositol (FC = 1.48), hypoxanthine (FC = 1.45), acetate (FC = 0.73) and malonate (FC = 1.35) as metabolites significantly different between groups. In conclusion, the present data showed that CHI changes the muscle metabolism improving muscle mass deposition, the lamb’s performance and carcass dressing. In addition, CHI led to an alteration in the FA metabolism, changes in the meat FA profile and improvements in meat quality.

The effect of the presence of rams upon the blood LH levels of ewes just at the start of the breeding season has been studied. It was found that there was a large and sudden increase in LH levels of ewes exposed to rams when compared to a control group. There were also small but non-significant effects on the mean date of the start of the breeding season and upon the number of lambs born.

Effects of daily food intake (FI) on daily gain (DG), food conversion ratio (FCR), ultrasonic backfat thickness (BF), proportion of lean parts (LP), proportion of fatty parts (FP), lean tissue growth rate (LTGR), fatty tissue growth rate (FTGR) and lean tissue food conversion (LTFC) were investigated in 687 barrows and 98 gilts, slaughtered at a mean live weight of 108 kg and fattened in seven batches. In the range of food intake from about 1·7 to 3·2 kg/day (22 to 42 MJ digestible energy) a continuous distribution of data was available.

Body composition was linearly related to FI. Most regressions of BF and all of LP and of FP on FI were linear, showing fatter animals at higher food intake. For FTGR, BF, LP and FP, parameter estimates based on linear regression were given. Although the response of DG and of LTGR on increasing FI was not always significantly different from linearity, the second degree polynomials indicated diminishing returns in all batches. FTGR had a high linear correlation with FI (0·85 to 0·95), indicating that in the present range of FI a rather fixed proportion of the food was used to deposit fatty tissue.

For DG and LTGR a non-linear model of the type a(FI -fo)b was fitted, where fo was interpreted as maintenance requirement. For FCR and LTFC the corresponding model was FI/(α(FI — fo)b). Both models were preferred over second degree polynomials because of better interpretation of parameters. FCR and LTFC showed minima at about 2·6 and 2·2 kg/day food intake, but especially for FCR the increase at increasing FI was low. Results were not consistent in demonstrating or refuting a plateau in LTGR, which in any event appears to lie near to or beyond ad libitum FI for most pigs.

Karakul, Mehraban, Naeini and Bakhtiari sheep were checked twice a day for oestrus using aproned rams and were laparotomized within 5 to 16 h of the end of every second oestrous period. Oestrus was observed for 12 monthly periods commencing on 21 April.

The Mehraban breed with 1 -6 oestrous periods per month was less seasonal in its breeding activity (P<0·01) than the other breeds. Four-year-old ewes were more sexually active (P<0·01) than 3-year-old ewes (1·48 v. 1·28 oestrous periods per month). Seasonal variation in the sexual activity of the ewes was observed (P<001); the peak of activity in July to January was followed by a steady decline in February and March to a low in April and May, and then a steep recovery phase in June. There was only limited sexual activity for at least 4 months (March to June).

The overall mean cycle length was 17·8 days (14 to 23 days), and the means for the four breeds were 17·6, 17·8, 17·8 and 17·9. The oestrous cycle was longer (P<0·05) during the period from December t o February than during that from June to August.

The overall mean duration of the oestrous period was 36·9 h and the means for the four breeds were 35·2, 38·0, 37·4 and 37·1 h, respectively (P<0·05). The duration showed some monthly variation (P<0·01) but did not follow a special seasonal pattern. The ovulation rates for the four breeds were 1·07, 1·13,0·94 and 0·95 respectively, (P<0·01). There was a non-significant decline in the mean ovulation rate from March to June. Right ovaries were more active than left ovaries as judged by the observation of a higher average number of corpora lutea per ewe per laparotomy (0·58 v. 0·43, P<001).

Twenty-four pigs were weaned at 21 days of age and given restricted feed allowances for the subsequent 8 days. Eight suckled pigs served as control and gained 320 g daily, of which approximately 40 g were lipid and 40 g protein. Pigs were slaughtered at 2-day intervals, physically dissected into non-carcass, carcass fatty tissue and carcass muscle plus bone, and these fractions were then analysed for water, protein and lipid. On average, weaned pigs made small positive body-weight gains. In comparison with suckled pigs, weaned pigs contained more water and less lipid but the same protein, and more non-carcass and less carcass fatty tissue but similar carcass muscle plus bone. Losses of lipid were offset by gains of water and associated with an increase in the percentage water content of carcass fatty tissue. At zero weight gain, pigs lost 43 g carcass fatty tissue, gained 37 g non-carcass, lost 56 g lipid and gained 53 g water, while carcass muscle plus bon e and protein gains were themselves not significantly different from zero. No change in carcass fatty tissue weight was associated with counterbalancing losses of lipid (18 g) and gains of water (15 g) and protein (3g). Lipid catabolism to support anabolism of essential body tissues commenced in the weaned pigs when weight gains fell below 193 g/day; this was about two-thirds of the gains achieved by the suckled control pigs. Plasma free fatty acid concentrations indicated that maximum lipid catabolism to occur on the 2nd day after weaning, and to reduce thereafter as body fat stores were progressively depleted.

The effect of genotype on the size of adipocytes and on the lipogenic enzyme activities in different fat depots in Asturiana, Avilena, Morucha, Parda Alpina, Pirenaica, Retinta and Rubia Gallega steers was studied (six animals per breed). Steers were weaned at about 6 to 8 months of age and 220 to 260 kg live weight (LW). During the fattening period the steers were given commercial concentrates and straw, both ad libitum, until slaughter at 470 kg average LW. Adipocyte size and activity of the following lipogenic enzymes were studied: glycerol 3-phosphate dehydrogenase (G 3-PDH); fatty acid synthase (FAS); NADP-malate dehydrogenase (MD), glucose 6-phosphate dehydrogenase (G 6-PDH) and NADP-isocitrate dehydrogenase (ICDH) in the omental, perirenal, subcutaneous and intermuscular adipose depots. Also the perirenal fat depot was removed and weighed and the 10th rib was dissected. Differences between breeds were significant for the amount of fat in the different adipose depots (P < 0·001), for adipocyte size (except in intermuscular depot) and for G 3-PDH, FAS, MD, ICDH (P < 0·001) and G 6-PDH (P < 0·01). In general, steers of breeds that had more fat also had bigger adipocytes and higher lipogenic enzyme activities. In this way, Asturiana breed (lean breed) had smaller adipocytes and lower lipogenic enzyme activities than Morucha breed (fatter breed). Finally, adipocytes from the perirenal depot were the biggest and showed the highest G 3-PDH and FAS activities while adipocytes from the intermuscular depot had the smallest size and the lowest lipogenic activities.

Avilamycin (AGP) and zinc oxide (ZnO) are both frequently included in the post-weaning piglet diet to enhance growth performance and prevent diarrhoea. This study investigated what effect removing these compounds from the post-weaning diet would have on the growth performance and faecal microbiota of weaned piglets. Fifty-two crossbred piglets (JSR Healthbred) were allocated, at weaning, to one of two dietary treatments on the basis of weight, litter origin and gender. The diets were (i) control (no supplemented ZnO or AGP); (ii) ZnO + AGP (supplemented with 3100 mg ZnO per kg food and 40 mg avilamycin per kg food). These diets were offered ad libitum for 20 days post weaning. Thereafter, the pigs received the same non-supplemented grower and finisher diets ad libitum. All piglets were individually weighed, and faecal samples were obtained from pre-selected piglets, at various time points throughout the trial period. Ten-fold serial dilutions of faecal material were cultured on specific media to enumerate aerobes, anaerobes, Lactobacillus spp. and Escherichia coli. ZnO + AGP supplementation enhanced weaned piglet average daily food intake (ADFI) (P < 0·001), average daily live-weight gain (ADG) (P < 0·001) and food conversion ratio (FCR) (P < 0·01) during the initial 20 days post weaning. Piglets previously supplemented with ZnO + AGP gained more weight per day during the non-supplemented grower phase (days 21 to 60) than their control counterparts (741·5 v. 672·5 g per pig per day) (P < 0·01). The bacteriological data showed that ZnO + AGP piglets had lower counts of anaerobic bacteria in their faeces than control piglets (P < 0·01). These findings indicate that dietary AGP + ZnO may enhance growth by reducing gastro-intestinal bacterial populations, and that their removal from the post-weaning diet will increase days to slaughter.

Egg storage longer than 7 days is associated with negative effects on hatchability traits. Pre-storage incubation has been a suggested method to reduce the negative effects of long-term storage times by enhancing the developmental stage of the embryo and probably reducing the embryonic stress. The objective of the present study was to investigate the effects of pre-storage incubation and storage time on hatchability characteristics, chick quality and serum thyroid hormones, antioxidative properties and immunoglobulin Y (IgY) concentrations of newly hatched chicks at two breeder flock ages. A total of 8000 fertile eggs were obtained from two different ages of chicken breeder hens (Egyptian local cross, Inshas). Half of the eggs were collected from young breeder hens (28 weeks old) and the other half from old breeder hens (50 weeks old). In each breeder flock age, eggs were distributed in a completely randomized experimental design in a 2×4 factorial arrangement, with two storage periods (4 or 14 days) and four pre-storage incubation durations (0, 4, 6 or 8 h at 37.5°C). At 28 and 50 weeks of age, pre-storage incubation and its interaction with storage period influenced significantly the apparent fertility, hatchability of set eggs and hatchability of fertile eggs and this improvement in hatchability is attributed to the reduction in embryonic mortality (early, intermediate and late). Pre-storage incubation for 6 or 8 h elevated significantly the grade A chicks and reduced the grade B chicks in comparison with non-heated controls. Interestingly, for eggs stored for 14 days, pre-storage incubation for 6 or 8 h enhanced serum triiodothyronine, thyroxine, glutathione peroxidase activity, total antioxidant capacity and IgY concentrations significantly and decreased serum malondialdehyde concentration significantly in the newly hatched chicks. It could be concluded that pre-storage incubation enhanced the hatching results, improved the antioxidative properties, reduced lipid peroxidation and elevated the humoral immunity in the newly hatched chicks. Hence, several benefits might be gained by pre-storage incubation when fertilized eggs will be stored for long periods.

Short-chain fatty acids (SCFAs) play a regulatory role in various physiological processes in mammals and act as endogenous ligands for the G protein-coupled receptors (GPR) 41 and 43. The role of GPR41 and GPR43 in mediating SCFA signaling in the rabbit remains unclear. The present study was to investigate the sequence of the GPR41 and GPR43 messenger RNA (mRNA) and their expression pattern in different tissues and developmental stages in New Zealand rabbit. Comparison of genomic sequences in GenBank using the Basic Local Alignment Search Tool program suggested that the New Zealand rabbit GPR41 mRNA has high similarities with the human (84%), bovine (84%) and Capra hircus (84%) genes. Similarly, GPR43 mRNA has high similarity with the rat (84%) and mouse (84%) genes. Real-time PCR results indicated that GPR41 and GPR43 mRNA were expressed throughout rabbit’s whole development and were expressed in several tissues. G protein-coupled receptor 41 and GPR43 mRNA were most highly expressed in pancreas (P<0.05) and s.c. adipose tissue (P<0.05), respectively. The expression levels of GPR41 mRNA was down-regulated in duodenum, cecum (P<0.05) and pancreas and up-regulated in jejunum, ileum, adipose tissue and spleen during growth. G protein-coupled receptor 43GPR43 mRNA was highly expressed in the duodenum, jejunum, ileum, colon, cecum and lung at 15th day (P<0.05), whereas the expression levels in the pancreas and spleen increased later after birth, with the highest expression at 60th day (P<0.05).

The effects of three variables; polysaccharidase inclusion level (0, 5 and 10 g/kg), moisture content (500, 600 and 700 g/kg dry matter (DM), and particle size (20, 5 and 2 mm), on the quality and degradation characteristics of ensiled rice straw were investigated. The polysaccharidase product used was shown to contain a broad spectrum of activities against polysaccharides typical of plant material. The major activities present being: mixed link glucanase, xylanase and both endo- and exo-cellulase. The straw treated with polysaccharidase had a lower final pH (5·21, 4·87, 4·82; P < 0·01), higher concentrations of lactic acid (1·98, 3·90, 3·67 g/kg; P < 0·01), a lower content of neutral-detergent fibre (689, 630, 621 g/kg DM; P < 0·01) and a higher solubility, measured as washing losses from nylon bags (152, 196, 212 g/kg DM; P < 0·01) for the 0, 5 and 10 g/kg polysaccharidase treatments respectively. The samples were subsequently incubated in nylon bags in the rumen of three sheep for 8, 16, 24, 48 and 72 h to estimate degradation rate and potential degradability using the expression p = a + b (1 – e−ct) where p is degradability at time t and a, b and c are constants. While there was no effect of moisture content or physical form of the straw, the degradation rate constant (c) was increased (P < 0·01) by the addition of polysaccharidase. The maximum potential degradability (a + b), however, was not altered by any of the treatments. The values for c were 0·0498, 0·0677 and 0·0817 per h and for (a + b) were 62·4, 62·1 and 62·8 g/100 g DM for the 0, 5 and 10 g/kg polysaccharidase enzyme additions respectively. It is concluded that the use of polysaccharidase enzymes can assist in the preservation of wet straw and can result in improved degradation characteristics.

The effects on rabbit welfare of transport in two seasons (summer and winter) and at two stocking densities (high stocking density: 12 rabbits per cage; low stocking density: 8 rabbits per cage) were studied. The loss of live weight during transport was calculated. At slaughter, blood samples were obtained and some physiological parameters related to stress were analysed: cortisol, creatine kinase (CK), lactate dehydrogenase (LDH), lactate, glucose, packed cell volume (PCV), osmolarity, and albumin and globulin concentrations. In addition, liver and muscle samples were taken and immediately frozen in liquid nitrogen for subsequent glycogen measurements.

Season significantly affected the live-weight losses and plasma concentrations of cortisol (P < 0.01), CK, LDH, lactate (P < 0.001) and glucose (P < 0.01), as well as osmolarity (P < 0.001). Liver and muscle glycogen concentration were also affected by the season (P < 0.001). The loss of live weight was higher in rabbits transported in winter than in summer. The plasma concentrations of cortisol, lactate and glucose, CK and LDH activity, and osmolarity, as well as liver and muscle glycogen concentrations were higher in rabbits transported in summer than in winter. Stocking density had no effect on the analysed parameters. The high levels of the analysed blood parameters, which are related to stress, lead to the conclusion that the welfare of the rabbits transported in summer was more affected than those transported in winter.

Mature non-lactating cows, 18-month-old heifersand7-month-oldfemale calves of the Charolais breed (eight animals of each age) were strip-grazedon short (S, sward surface height: 7·5 cm), medium (M,10·2 cm) and tall (T, 21·1 cm) cocksfoot (Dactylis glomerata) swards at a daily herbage allowance of 40 g dry matter per kg live weight over three 15-day experimental periods. The swards were leafy regrowths of 1 (S), 2 (M)and 3·5 (T)weeks of age. Herbage intake was estimated by the n-alkane method, and grazing behaviour was recorded visually.

Intakes per kg live weight of calves and heifers were higher than those of cows on all swards(P < 0·01). Calves tended to maintain intake, whereas cows and heifers reduced their intake as sward height decreased. Bite weight decreased linearly with sward height, this decrease being greater for larger animals (P < 0·001). As sward height decreased, the scaling factor of bite weight to live weight decreased. Biting rates increased as sward height decreased (P < 0·001) and were lower in calves than in older cattle (P < 0·001). Calves had lower intake rates per kg live weight than cows in T swards, and the reverse was true in S swards (P < 0·001). Younger cattle always grazed longer than cows, but differences were reduced as sward height decreased (P < 0·01). Cows and heifers wereunable to increase their grazing time sufficiently to compensate for lower intake rates in S and M swards, resulting in reduced herbage intakes. Faecal markers and grazing behaviour suggested a greater selectivity by calves compared with older cattle.

Two experiments were carried out with growing-fattening bulls, offered a fattening diet based on concentrate and supplemented with soya oil or steam-flaked linseed. Soya oil (200 g/kg) was mixed with middlings (800 g/kg). Linseed (500 g/kg) and whole barley (500 g/kg) were steam flaked. The fat incorporation resulted in an increase of the ether extract content from 26·5 g/kg dry matter to about 45 g/kg. The incorporation of soya oil increased the average daily gain (P > 0·05). The saturated: unsaturated fatty acid ratio was reduced in perirenal fat due to an increase of oleic acid and a reduction of stearic acid. The inclusion of steam-treated linseed resulted in a lower slaughter weight (P < 0·05) and a shorter fattening period (P > 0·05). The fatty acid composition of perirenal fat was affected significantly: the concentrations of oleic, linoleic and linolenic acid were increased and the concentrations of myristic, palmitic and stearic acids were reduced. This resulted in a reduced saturated: unsaturated fatty acid ratio.

In a third experiment, samples of the two fat concentrates were incubated in nylon bags in the rumen. The ether extract disappearance was high with both concentrates. Furthermore, the fatty acid composition was altered to a large extent for soya oil while large proportions of unsaturated fatty acids were still present with steam-flaked linseed.

A procedure for maximizing genetic gain (after a number of generations of selection) for a given rate of inbreeding or for a given coefficient of variation of response is presented. An infinitesimal genetic model is assumed. Mass selection is practised for a number of discrete generations. With constraints on inbreeding, expected rates of genetic progress (ΔG) are combined with expeced rates of inbreeding (ΔF) in a linear objective function (Ω = ΔG - μΔF). In addition, an expression to approximate the rate of gain at any generation accounting for changes in genetic parameters due to linkage disequilibrium and due to inbreeding is derived. Predicted gain is in general within 5% of that obtained from simulation. Thus, both ΔG and ΔF are obtained from simple analytical formulae. An equivalent function is used when the coefficient of variation of response (CV) is the parameter restricted (Ω = ΔG -μCV). Maximization of the objective function Ω for appropriate values of μ gives the optimum number of sires and dams selected when specific constraints on the level of inbreeding or the coefficient of variation of response are imposed. The method is applied to a practical situation in fish breeding. Optimum mating ratios and optimum numbers of sires selected are obtained for different scored population sizes and heritabilities. Results obtained with this procedure agree very well with results from simulation studies. The optimum number of sires increases with the size of the scheme and with more severe restrictions on risk. In the schemes considered, the optimum mating ratio is equal to 2 unless the constraint on the rate of inbreeding is severe, the size of the scheme is small and the heritability is low. In these situations the optimum mating ratio is equal to 1. The procedure is general in terms of generations of selection considered and in terms of parameters to be constrained. A large amount of computer processor unit time is saved with this method in comparison with simulation procedures.

An investigation was conducted to compare, the LH, prolactin and progesterone profiles of ewe lambs with ewes during oestrus and early pregnancy. Peak LH concentration was significantly lower (P < 0·05) and duration of release tended to be shorter during oestrus in ewe lambs. Furthermore, this smaller LH peak tended to be associated with a lower ovulation rate. LH pulse rate, amplitude and concentration were similar in both groups during day 13 of pregnancy. However, LH concentration was higher in ewe lambs compared with ewes on day 28 of pregnancy. Peak prolactin concentration was lower during oestrus in ewe lambs (P < 0·05) but there was no difference between the two groups during early pregnancy. Plasma progesterone concentrations were similar in both groups until day 13 of pregnancy. Thereafter, mean progesterone concentration was lower, from day 14 to 30, in the ewe lambs (P < 0·05). These results indicate that in ewe lambs and ewes maintained under identical conditions plasma hormone profiles differ during oestrus and early pregnancy. Moreover, these differences probably contribute towards the lower reproductive performance of ewe lambs.

The aim of this study was to investigate the effects of different levels of cadmium supplementation (0, 5, 10, 20, 40 and 80 mg/kg) in the diet on performance, egg quality, tibia biomechanical properties and eggshell and bone mineral contents in laying quails. In this 10-week trial, a total of 96 laying quails, aged 21 weeks, were randomly distributed among six experimental groups. Each experimental group contained four replicates of four birds each. The performance parameters were adversely affected quadratically when cadmium was added to the diets in the concentrations of 20 mg/kg and above (P<0.01). The specific gravity and eggshell weight were maximal with the addition of 20 mg/kg cadmium to the diet. The biomechanical properties of the tibia were negatively affected by cadmium supplementation in quails (P<0.05). The eggshell boron content decreased linearly (P<0.001) with cadmium supplementation to the diet. The cadmium content in bone increased when cadmium was added to the diets (P<0.001). The bone boron concentration decreased as dietary cadmium supplementation was increased (P<0.001).

Forage halophytes such as saltbush (Atriplex spp.) are widely used to revegetate Australian saline land and can provide a medium-quality fodder source. An animal house experiment was conducted to investigate differences in the carcass and eating quality of sheep ingesting saltbush from saline land in combination with a barley supplement. Twenty-six merino hoggets (two groups of 13) were fed either a 60 : 40 dried saltbush (Atriplex nummularia): barley (S + B) ration or a 33 : 25 : 42 lupins : barley : oaten hay ration (C) for 10 weeks prior to commercial slaughter. After 10 weeks, all sheep were commercially slaughtered and a single loin (from 12th rib to chump) collected from each animal for taste-panel analysis. Carcass weight, total tissue depth over the 12th rib 110 mm from the midline (GR fat depth), ultimate pH and colour were determined and X-ray bone densitometry used to estimate the fat content of the carcass. Blood samples were taken to assess the hormonal response to ingesting these diets and fatty acid profiles of the subcutaneous and intramuscular fat were determined. Both groups grew at the same rate (62 g/day) and had similar hot carcass weights (P > 0.01) (17.2 ± 0.3 kg for S + B and 17.9 ± 0.3 kg for C). However, these live weights may not be high enough to be commercially viable such that saltbush and barley may only be suitable as a maintenance feed. The S + B-fed sheep had a significantly (P = 0.055) lower fat and higher lean content (P < 0.05) than the C group. This is a positive finding as fat denudation is a significant cost to processors and farmers can produce sheep that are depositing less fat or more lean per unit of live-weight gain. The decreased fat and increased lean content were attributed to the higher protein : energy ratio available for production and lower circulating insulin and higher growth hormone of the S + B-fed sheep. The lower body-fat content and lower metabolisable energy and digestible organic matter intake did correlate with the sheep fed the S + B diet, having a significantly lower percentage of unsaturated fat and equal levels of saturated fat than the C treatment. Diet had no effect on the ultimate pH or colour of the meat. Treatment had no significant effect on any of the eating-quality attributes (P > 0.1). The drying of the saltbush, the shorter length of the experimental period and the low carcass fat content were believed to have contributed to this result. Further field experiments are needed to clarify the benefits to carcass and eating quality of ingesting saltbush.

The effect of dietary lipids and Clostridium butyricum supplementation on circulating lipids and the transcription of selected genes involved in lipid metabolism were investigated in broiler chickens. One hundred and sixty-day-old broilers (Arbor Acres) were divided into four treatment groups in a 2 × 2 factorial arrangement and fed four diets with two lipid sources (soybean oil or fish oil) and two levels of C. butyricum (0 or 5 g/kg) for a period of 6 weeks. Serum concentrations of total cholesterol and low-density lipoprotein cholesterol were lower (P < 0.05) in broilers fed diets containing fish oil than in those fed diets containing soybean oil. Fish oil significantly reduced (P < 0.05) hepatic fatty acid synthase and lipoprotein lipase (LPL) activities in abdominal fat. In contrast, fish oil significantly increased (P < 0.05) breast muscle LPL activity and hepatic peroxisome proliferator-activated receptor-α and LPL gene expression. The addition of C. butyricum significantly increased (P < 0.05) LPL activity in abdominal fat and liver-type fatty acid-binding protein gene expression in jejunal mucosa. The results of this study indicated that the reduced abdominal fat in broilers fed fish oil as observed may be due to augmented hepatic fatty acid catabolism and lower hepatic fat synthesis. The increased intramuscular fat content in breast muscle of broilers fed C. butyricum as described may be the result of enhanced fatty acid uptake.

Poultry production is an important way of enhancing the livelihoods of rural populations, especially in low- and middle-income countries (LMICs). As poultry production in LMICs remains dominated by backyard systems with low inputs and low outputs, considerable yield gaps exist. Intensification can increase poultry productivity, production and income. This process is relatively recent in LMICs compared to high-income countries. The management practices and the constraints faced by smallholders trying to scale-up their production, in the early stages of intensification, are poorly understood and described. We thus investigated the features of the small-scale commercial chicken sector in a rural area distant from major production centres. We surveyed 111 commercial chicken farms in Kenya in 2016. We targeted farms that sell the majority of their production, owning at least 50 chickens, partly or wholly confined and provided with feeds. We developed a typology of semi-intensive farms. Farms were found mainly to raise dual-purpose chickens of local and improved breeds, in association with crops and were not specialized in any single product or market. We identified four types of semi-intensive farms that were characterized based on two groups of variables related to intensification and accessibility: (i) remote, small-scale old farms, with small flocks, growing a lot of their own feed; (ii) medium-scale, old farms with a larger flock and well located in relation to markets and (iii) large-scale recently established farms, with large flocks, (iii-a) well located and buying chicks from third-party providers and (iii-b) remotely located and hatching their own chicks. The semi-intensive farms we surveyed were highly heterogeneous in terms of size, age, accessibility, management, opportunities and challenges. Farm location affects market access and influences the opportunities available to farmers, resulting in further diversity in farm profiles. The future of these semi-intensive farms could be compromised by several factors, including the competition with large-scale intensive farmers and with importations. Our study suggests that intensification trajectories in rural areas of LMICs are potentially complex, diverse and non-linear. A better understanding of intensification trajectories should, however, be based on longitudinal data. This could, in turn, help designing interventions to support small-scale farmers.

Mastitis is one of the most prevalent and costly diseases in dairy cattle. Key components for adequate mastitis control are the detection of early stages of infection, as well as the selection of appropriate management interventions and therapies based on the causal pathogens associated with the infection. The objective was to characterize the pattern of electrical conductivity (EC) in milk during intramammary infection, considering specific mastitis-causing pathogen groups involvement. Cows (n = 200) identified by an in-line mastitis detection system with a positive deviation ≥15% in the manufacturer’s proprietary algorithm for EC (high electrical conductivity (HEC)) were considered cases and enrolled in the study at the subsequent milking. One control (CON) cow, within normal ranges for EC, was matched to each case. A composite milk sample was collected aseptically from each cow for bacteriological culture. Milk yield (MY) and EC were recorded for each milking during ±7 days relative to enrollment. Milk cultures were categorized into gram positive (GP), gram negative (GN), other (OTH) and no growth (NOG). Data were submitted for repeated-measures analysis with EC as the dependent variable and EC status at day −1, bacteriological culture category, parity number, stage of lactation and days relative to sampling as main independent variables. Average (± standard error (SE)) EC was greater in HEC than in CON cows (12.5 ± 0.5 v. 10.8 ± 0.5 mS/cm) on the day of identification (day −1). Milk yield on day −1 was greater in CON than in HEC (37.6 ± 5.1 v. 33.5 ± 5.2 kg). For practical management purposes, average EC on day −1 was similar for the different bacteriological culture categories: 11.4 ± 0.6, 11.7 ± 0.5, 12.3 ± 0.8 and 11.7 ± 0.5 mS/cm in GN, GP, OTH and NOG, respectively. Parity number was only associated with day −1 EC in HEC group, with the greatest EC values in parity 3 (12.3 ± 0.3 mS/cm), followed by parity 2 (11.9 ± 0.2 mS/cm), parity >3 (11.6 ± 0.5 mS/cm) and primiparous cows (11.2 ± 0.2 mS/cm). An effect on EC for the interaction of day relative to identification by pathogen gram category was observed. The same interaction effect was observed on daily MY. Overall, the level of variation for MY and EC between- and within-cows was substantial, and as indicated by the model diagnostic procedures, the magnitude of the variance in the cows in the CON group resulted in deviations from normality in the residuals. We concluded that characteristic temporal patterns in EC and MY in particular pathogen groups may provide indications for differentiation of groups of mastitis-causing pathogens. Further research to build detection models including EC, MY and cow-level factors is required for accurate differentiation.