Impact of growth curve and dietary energy-to-protein ratio of broiler breeders on offspring quality and performance

The impact of growth curve (GC) and dietary energy-to-protein ratio of broiler breeder hens on chick quality and broiler performance was investigated. Pullets (n = 1,536) were randomly allotted to 24 pens and assigned to 1 of 8 treatments from hatch onwards, according to a 2 × 4 factorial arrangement with 2 GC (standard growth curve = SGC or elevated growth curve = EGC, +15%) and 4 diets, differing in energy-to-protein ratio (96%, 100%, 104%, and 108% AME_n diet). At 28 and 36 wk of age, 60 hatching eggs per maternal pen were selected for incubation and 768-day-old broilers were assigned to 32 pens according to maternal treatment.

Broilers from EGC breeders were 1.9 g heavier at hatch (P < 0.001) and 36 g heavier at slaughter (P = 0.001) than broilers from SGC breeders due to a 1.0 g/d higher growth rate (P = 0.003) and 1.5 g/d higher feed intake (P = 0.006) from hatch to 32 d of age. An increase in breeder dietary energy-to-protein ratio resulted in a linear decrease in embryonic mortality in the first 3 d of incubation (β = -0.2% per % AME_n; P = 0.05). At hatch, broiler BW decreased with an increasing breeder dietary energy-to-protein ratio (β = -0.1 g per % AME_n; P = 0.001), whereas at slaughter broiler BW increased with an increasing breeder dietary energy-to-protein ratio (β = 3.2 g per % AME_n; P = 0.02). This was due to a linear increase in growth rate (β = 0.1 g/d per % AME_n; P = 0.004) and feed intake (β = 0.1 g/d per % AME_n; P = 0.02). Additionally, an increase in breeder dietary energy-to-protein ratio resulted in a linear decrease in body weight corrected feed conversion ratio (β = -0.002 per % AME_n; P = 0.002). Overall, it can be concluded that a higher GC of breeders and an increase in breeder dietary energy-to-protein ratio enhances offspring performance.

Early Phenotype Programming in Birds by Temperature and Nutrition: A Mini-Review

Early development is a critical period during which environmental influences can have a significant impact on the health, welfare, robustness and performance of livestock. In oviparous vertebrates, such as birds, embryonic development takes place entirely in the egg. This allows the effects of environmental cues to be studied directly on the developing embryo. Interestingly, beneficial effects have been identified in several studies, leading to innovative procedures to improve the phenotype of the animals in the long term. In this review, we discuss the effects of early temperature and dietary programming strategies that both show promising results, as well as their potential transgenerational effects. The timing, duration and intensity of these procedures are critical to ensure that they produce beneficial effects without affecting animal survival or final product quality. For example, cyclic increases in egg incubation temperature have been shown to improve temperature tolerance and promote muscular growth in chickens or fatty liver production in mule ducks. In ovo feeding has also been successfully used to enhance digestive tract maturation, optimize chick development and growth, and thus obtain higher quality chicks. In addition, changes in the nutritional availability of methyl donors, for example, was shown to influence offspring phenotype. The molecular mechanisms behind early phenotype programming are still under investigation and are probably epigenetic in nature as shown by recent work in chickens.

Direct and maternal reduced balanced protein diet influences the liver transcriptome in chickens

The objective of this study was to evaluate, by means of RNA sequencing, the direct and transgenerational effect of a reduced balanced protein (RP) diet on broiler breeder metabolism. Chickens of the F0 generation were fed a control (C) or RP diet, and their F1 progeny was fed a C or RP diet as well, resulting in four groups of chickens: C/C, C/RP, RP/C and RP/RP. While both direct and maternal effects were seen on body weight, breast muscle weight and abdominal fat weight in the F1 generation, the direct effect was the most dominant one. The liver transcriptome in the F1 generation showed that amino acid metabolism was up-regulated in chickens that received the control feed when compared with their respective contemporaries that received the reduced protein diet. Interestingly, chickens hatched from control-fed hens but reared on the reduced protein diet (C/RP group) activated a fatty acid metabolism, expressing more fatty acid desaturase 1 gene, fatty acid desaturase 2 gene and elongation of very long-chain fatty acids protein 2 gene, when compared with control-fed chickens hatched from control-fed hens (C/C group), while chickens hatched from reduced protein-fed hens that received themselves the same reduced protein diet (RP/RP group) triggered their glucose metabolism more, showing elevated levels of phosphofructokinase gene, 6-phosphofructo-2-kinase/fructose-2,6-biphospatase 4 and fructose-biphosphate aldolase C mRNA compared with the chickens hatched from reduced protein-fed hens but reared on a control diet (RP/C group). This suggests that the maternal protein diet has an impact on the metabolism of broilers when they are reared on a RP diet.

Interaction of CP levels in maternal and nursery diets, and its effect on performance, protein digestibility, and serum urea levels in piglets

Reduced protein levels in nursery diets have been associated with a lower risk of postweaning diarrhea, but the interaction with CP levels in maternal diet on the performance of the offspring remains unclear. The objective of this study was to determine the effect of protein content in sow gestation and piglet nursery diets on the performance of the piglets until slaughter. This was studied in a 2 × 2 factorial trial (35 sows, 209 piglets), with higher or lower (H or L) dietary CP in sow diets (168 vs 122 g CP/kg) during late gestation. A standard lactation feed was provided for all sows (160 g CP/kg). For both sow treatments, half of the litters received a higher or lower CP in the piglet nursery diet (210 vs 166 g CP/kg). This resulted in four possible treatment combinations: HH, HL, LH and LL, with sow treatment as first and piglet treatment as second letter. For each phase, all diets were iso-energetic and had a similar level of essential amino acids. P_s*p is the p-value for the interaction effect between sow and piglet treatment. In the nursery phase (3.5-9 weeks of age), a tendency toward interaction between piglet and sow treatments with feed efficiency (P_s*p = 0.08) was observed with HH having the highest gain:feed ratio (G:F) (0.74 ± 0.01), LH the lowest (0.70 ± 0.01) and the other two groups intermediate. In the growing-finishing phase, an interaction was observed between the piglet and sow diets with decreased G:F for LH (P_s*p = 0.04) and a tendency toward interaction with increased daily feed intake for LH (P_s*p = 0.07). The sow diet showed a tendency toward a long-lasting effect on the dressing percentage and meat thickness of the offspring, which was higher for the progeny of H sows (P_s < 0.01 and P_s = 0.02, respectively). At 23 weeks, serum urea concentrations tended to be lower for the HH and LL groups (P_s*p = 0.07). Fecal consistency scores were higher at day 10-day 14 after weaning for piglets from L sows (P_s = 0.03 and P_s < 0.01, respectively). At day 7 after weaning, fecal consistency score was higher for piglets fed the higher protein diet (P_p < 0.01). At 8 weeks of age, the apparent total tract digestibility of CP (ATTD_CP) interacted between piglet and sow diet (P_s*p = 0.02), with HH showing the highest digestibility values. In conclusion, the protein levels in sow late-gestation and piglet nursery diets interacted with feed efficiency, ATTD_CP and serum urea concentrations in the nursery phase.

Management factors resulting in a severe reduction in feed intake-induced spiking mortality syndrome in young broiler chicks

This study aimed to induce spiking mortality syndrome (SMS) in 10-day-old broiler chicks by changing feed particle size (crumble feed to pellet feed) and/or feed source location (from a small feeder at the pen's center to a large feeder at the front of the pen), followed by full day feed deprivation of all broiler chicks on day 11. In total, 396-day-old male Ross 308 broiler chicks were randomly assigned to 4 treatments (Con: without change in feed particle size and feed source location; Par: changing crumble feed to pellet feed on day 10; Loc: changing feed source location on day 10; LocPar: changing both feed particle size and feed source location on day 10). Each treatment consisted of 9 replicate pens with 11 chicks each. Each treatment was applied at 09:00 on days 10 and 11. On both days, chicks with SMS were identified based on clinical symptoms (down in sternal or lateral recumbency, hyperventilation). Plasma glucose, 3, 3′, 5-triiodothyronine (T₃), thyroxine (T₄) concentrations, insulin, and liver glycogen concentrations of chicks without (normal) and with SMS were measured. Proportional organ and digestive tract including content weights were recorded. Broiler behavior was assessed hourly from 08:30 to 17:30 on day 10. On day 10, the Par, Loc, and LocPar groups spent significantly less time feeding and more time lying down compared with the Con group. On days 10 and 11, SMS clinical signs were observed around 2.5 to 3.5 h after the initiation of treatments, and the Loc group had the most SMS morbidity level. Spiking mortality syndrome chicks had significantly less digestive tract contents compared with Normal chicks on day 10. Spiking mortality syndrome was induced successfully with the treatments, according to their significantly reduced plasma glucose, insulin, T3 and T4 concentrations as well as liver glycogen content. A significant correlation between plasma glucose and liver glycogen was observed in SMS chicks. In conclusion, management factors inducing the reduction or absence of feed intake on day 10 or day 11 can trigger the occurrence of SMS in young broiler chicks.

Relative contribution of production chain phases to health and performance of broiler chickens: a field study

There is increasing evidence that health and performance of the breeder flock significantly contributes to health and performance of their progeny. Data of broiler performance and health are routinely collected in various stages of the broiler production chain. In the Netherlands, the broiler chain operates at a relatively non-integrated level and the various databases are usually not connected. Connecting databases may however provide important information to improve chain performance. The aim of the present study was to determine systematic effects of broiler breeder production farm or flock on health (mortality and antibiotics use) and performance of their offspring, using data routinely collected at the different stages of the production chain. Broiler flock data collected over 6 yr (daily growth, slaughter weight, carcass weight uniformity, carcass condemnations, first week and total mortality, and antibiotics use) were linked to breeder flocks and farms. In total, 2,174 broiler flock records (at house level) of 74 broiler farms were linked to 88 broiler breeder farms and 209 breeder flocks. A mixed model analysis was applied to simultaneously estimate effects of season, parent flock age, time trend, and the contribution of the different chain phases to broiler performance and health. No systematic effects of breeder farm and only small systematic effects of breeder flock on broiler health and performance were found. The largest breeder flock effect was found for carcass condemnations (estimated contribution to the variance component: 7%). Most variation on broiler health and performance was explained by broiler farm and “day-old chick batch.” The latter refers to the rest variance that could not be explained by other factors, i.e., incidental effects linked to the specific day-old chick batch and the stage between the breeder and broiler farm. Our results suggest that systematic effects of breeder flock and farm could have been overruled by (management in) the hatchery phase and the broiler farm. This indicates room for improvement of management in these production phases.

The effect of reduced balanced protein diet on the behavior of female broiler breeders in 2 generations

The behavior of 2 generations of broiler breeders undergoing a 25% reduced balanced protein (RP) dietary treatment was investigated in the current study. There were 2 treatments for the F0 generation: control (C) breeders fed with standard C diets and RP breeders fed with RP diets. The female progeny of each treatment was again subjected to 2 dietary treatments, resulting in 4 treatments for F1 generation: C/C, C/RP, RP/C, and RP/RP (breeder feed in F0/F1 generation). To maintain the target body weights throughout the trial, breeders on RP diet received on average 10% more feed than C diet breeders. The behavior of the breeders at 8h30 (30 min before feeding at 9h00), 12h00, and 15h30 in weeks 23 and 37 of the F0 generation and in week 6, 11, and 22 of the F1 generation was observed. Litter scratching, feather pecking, and object pecking were occasionally increased by RP diet feeding which indicated feeding frustration. Drinking behavior decreased dramatically by the RP dietary feeding and resulting in a better litter condition which could benefit dust bathing behavior. In addition, feeding the breeders RP diet in the F0 generation decreased litter scratching (week 6) and feather pecking (week 22, 15h30) but increased sitting (week 11, 15h30) and drinking (a tendency in week 6 and a significant effect in week 11) behavior of offspring breeders (F1 generation). In general, breeders fed with reduced balanced protein diets, to some extent, spent less time drinking and their offspring could have an adaptation to the maternal RP diet. The mechanism of this adaptation still needs to be further investigated. In general, positive effects were found by reducing protein level of breeder diets. However, negative side effects such as feeding frustration were also observed, which merit further study.