Feed Allocation Research Articles

Broiler breeders utilise body lipid as an energy source

The study was conducted to determine the extent to which broiler breeder hens could make use of excess body lipid reserves as a means of maintaining laying performance. The experiment was divided into two phases. In the first phase, the birds aged 37 weeks were allocated one of four daily allowances: 160, 175, 190 or 205 g of a commercial broiler breeder feed for a period of four weeks in order to achieve four levels of fatness in the hens. During the second phase, also lasting four weeks, the birds were given a high protein, low energy feed at three rates of allocation (120, 100 or 80 g/hen d). Performance was higher over the final two weeks of Phase 2 when birds were fed 120 g/d in this period, with production tending to decrease as allocations increased in Phase 1, although this was not significant. The same pattern of response was seen in birds given 100 g/d in the second phase of the trial, i.e. excessive lipid reserves tended to be detrimental to performance in these two treatments. However, where 80 g was allocated daily in Phase 2 this was clearly insufficient to sustain performance, but in this case egg production was considerably higher in birds that had been given larger amounts of food in Phase 1, and which could therefore draw on body lipid reserves as a source of energy. Rate of lay increased by 3.5% and egg output by 4.0 g/d for every additional 10 g of food given in Phase 1, as a result of lipid reserves having been utilised when daily food intake was severely depressed. Egg weight was not affected by any of the feed allocations until the last two weeks of the trial when birds fed 80 g/d started laying smaller eggs. Broiler breeders are capable of maintaining their egg production for short periods at an energy intake that is much lower than is recommended and this has implications when modelling the effect of food composition on performance of broiler breeder hens. Keywords: Lipid reserves, breeders, laying period

The effect of dietary crude protein on the fertility of male broiler breeders

Reports on the influence of dietary crude protein on male broiler breeder fertility are not consistent, and therefore an experiment was conducted to determine the effect of three isoenergetic diets containing 10.5%, 12.6% and 15% crude protein, respectively, on Ross broiler breeder male fertility from 26 to 41 weeks of age. Feed allocation was the same for each treatment, and was done according to breeder recommendations. Fertility was assessed by determining the number of sperm trapped in the outer perivitelline layer of eggs laid after artificial insemination with a fixed volume of semen collected from 12 males per treatment. Semen concentration, motility and morphology were also determined. Crude protein intake had a significant effect on the rate of decline in fertility post insemination. This resulted in a longer predicted length of the fertile period over all ages when eggs were fertilised with sperm obtained from males that received 12.6% CP diets (14.5 d) than males that received 10.5% and 15% CP (7 and 8.6 d respectively). There was, however, no treatment effect on the measures of live sperm with normal motility or morphology.Keywords: Cockerel, insemination, perivitelline membrane, nutrition, reproduction

Ka 대역 통신위성용 다중 빔 배열 급전 반사판 안테나

본 논문은 한반도 지역에 보편적 위성 통신 서비스를 제공하기 위한 정지궤도 위성의 다중 빔 서비스 커버리지 요구에 따라, 서비스 영역 내의 이득을 높일 수 있는 구현 가능한 안테나 구성 시나리오를 제안하였다. 제안된 시나리오는 위성 탑재가 가능하도록 안테나 및 급전 네트워크 구성을 간소화하고, 제한된 주파수 및 편파자원을 효율적으로 사용하기 위한 급전 네트워크 설계를 포함하고 있다. 또한, 전기적 성능 만족을 위하여 배열소자의 배치 및 여기 계수 최적화가 수행되었다. This paper presents the multibeam service coverage of GEO(Geostationary Orbit) satellite and the practical antenna scheme scenarios to provide the universal communication services on the Korean peninsula. The proposed antenna systems consist of the simplest scheme and feed network so that they can be mounted on satellites. The feed networks are effectively organized according to the frequency and polarization plan. Despite simple structure, all scenarios meet the electrical performance by the optimization of feed allocation and feed excitation.

Low‐Dose Hydrogen Peroxide Application in Closed Recirculating Aquaculture Systems

AbstractThe aim of the present work was to simulate water treatment practices with hydrogen peroxide (HP) in recirculating aquaculture systems (RAS). Six identical 1,700‐L pilot‐scale RAS were divided into two experimental groups based on daily feed allocation and operated under constant conditions for a period of 3 months. The organic and nitrogenous loadings of the systems differed fourfold between the two groups and were achieved by predefined constant daily feed loads and constant additions of water. The fixed cumulative feed burden was 1.6 × 103 mg feed/L in the low‐intensity RAS and 6.3 × 103 mg/L in the high‐intensity RAS. The decay of HP in rearing tanks and disconnected biofilter units was investigated by means of HP spiking experiments. The decay in high‐intensity RAS rearing units and biofilters was orders of magnitude faster than that in low‐intensity units. The application of HP impaired biofilter nitrite oxidation in low‐intensity RAS but not in high‐intensity RAS. The impact of HP exposure time on biofilter nitrification capacity was then assessed in biofilter bench‐scale experiments with nitrite spiking. Exposure time was found to significantly affect nitrite oxidation. Compared with unexposed biofilter elements, nitrite oxidation was reduced more than 90% following 3 h of exposure to 15 mg HP/L, whereas 30 min of exposure had only minor negative effects on nitrite oxidation. The findings of this study demonstrate the potential for developing HP water treatment practices for RAS and contradict prevailing notions that HP cannot be used safely in RAS that employ biofiltration. The development of effective new HP treatment protocols for recirculating aquaculture could reduce the current dependence on formalin to improve water quality and control parasitic loads.

Nutritional intervention during gestation alters growth, body composition and gene expression patterns in skeletal muscle of pig offspring

Variations in maternal nutrition during gestation can influence foetal growth, foetal development and permanently ‘programme’ offspring for postnatal life. The objective of this study was to analyse the effect of increased maternal nutrition during different gestation time windows on offspring growth, carcass quality, meat quality and gene expression in skeletal muscle. A total of 64 sows were assigned to the following feeding treatments: a standard control diet at a feed allocation of 2.3 kg/day throughout gestation, increased feed allowance of 4.6 kg/day from 25 to 50 days of gestation (dg), from 50 to 80 dg and from 25 to 80 dg. At weaning, Light, Medium and Heavy pigs of the same gender, within litter, were selected based on birth weight, individually penned and monitored until slaughter at 130 days post weaning. Carcass and meat quality traits of the semimembranosus (SM) muscle were recorded post mortem. A cross section of the semitendinosus (ST) muscle encompassing the deep and superficial regions were harvested from pigs (n = 18 per treatment) for RNA extraction and quantification of gene expression by real-time PCR. The results showed that doubling the feed intake from 25 to 50 dg reduced offspring growth, carcass weight, intramuscular fat content and increased drip loss of the SM muscle. Interestingly, protein phosphatase 3 catalytic subunit – α-isoform, which codes for the transcription factor calcineurin, was upregulated in the ST muscle of offspring whose mothers received increased feed allowance from 25 to 50 dg. This may provide an explanation for the previous observed increases in Type IIa muscle fibres of these offspring. Increasing the maternal feed intake from 50 to 80 dg negatively impacted pig growth and carcass weight, but produced leaner male pigs. Extending the increased maternal feed intake from 25 to 80 dg had no effect on offspring over the standard control gestation diet. Although intra-litter variation in pig weight is a problem for pig producers, increased maternal feeding offered no improvement throughout life to the lighter birth weight littermates in our study. Indeed, increased maternal nutrition at the three-gestation time windows selected provided no major benefits to the offspring.

A data envelope analysis to assess factors affecting technical and economic efficiency of individual broiler breeder hens

This study evaluated the effect of feed allocation and energetic efficiency on technical and economic efficiency of broiler breeder hens using the data envelope analysis methodology and quantified the effect of variables affecting technical efficiency. A total of 288 Ross 708 pullets were placed in individual cages at 16 wk of age and assigned to 1 of 4 feed allocation groups. Three of them had feed allocated on a group basis with divergent BW targets: standard, high (standard x 1.1), and low (standard x 0.9). The fourth group had feed allocated on an individual bird basis following the standard BW target. Birds were classified in 3 energetic efficiency categories: low, average, and high, based on estimated maintenance requirements. Technical efficiency considered saleable chicks as output and cumulative ME intake and time as inputs. Economic efficiency of feed allocation treatments was analyzed under different cost scenarios. Birds with low feed allocation exhibited a lower technical efficiency (69.4%) than standard (72.1%), which reflected a reduced egg production rate. Feed allocation of the high treatment could have been reduced by 10% with the same chick production as the standard treatment. The low treatment exhibited reduced economic efficiency at greater capital costs, whereas high had reduced economic efficiency at greater feed costs. The average energetic efficiency hens had a lower technical efficiency in the low compared with the standard feed allocation. A 1% increment in estimated maintenance requirement changed technical efficiency by -0.23%, whereas a 1% increment in ME intake had a -0.47% effect. The negative relationship between technical efficiency and ME intake was counterbalanced by a positive correlation of ME intake and egg production. The negative relationship of technical efficiency and maintenance requirements was synergized by a negative correlation of hen maintenance and egg production. Economic efficiency methodologies are effective tools to assess the economic effect of selection and flock management programs because biological, allocative, and economic factors can be independently analyzed.

A twice-a-day feeding regimen optimizes performance in broiler breeder hens

To evaluate the effects of different methods of feed allocation on performance, plasma hormone concentration, and ovarian morphology, an experiment was conducted using 32 Cobb 500 broiler breeder hens. The experiment was started at 27 wk and lasted to 39 wk of age. Feeding regimens included: i) hens with an ad libitum feeding program, ii) hens that received their restricted feed once a day, iii) hens that received their restricted feed twice a day, and iv) hens that received their restricted feed 3 times a day. Each hen was assumed as an experimental unit and treatments were replicated 8 times. Daily egg production, BW, and egg and yolk weights were measured. Two blood samples were taken 3 and 6 h after the first feed allocation every 2 wk. Plasma samples were assayed for glucose, triacylglycerol (TAG), cholesterol, as well as leptin-like concentration, glucagon, triiodothyronine, thyroxine, progesterone, estradiol, and testosterone. Liver, abdominal fat pad, and ovary were collected at necropsy. Ovaries were weighed and follicles were characterized as large yellow follicles, small yellow follicles, and large white follicles. Results showed inferior egg production in ad libitum-fed birds along with high levels of plasma glucose, TAG, cholesterol, leptin-like concentration, and testosterone. Twice-a-day-fed birds produced more egg in the entire production period than once-a-day-fed birds. Better performance of twice-a-day-fed hens was associated with lower plasma glucose, TAG, and leptin-like concentration, whereas their estradiol and glucagon were higher than once-a-day-fed hens. Results obtained in our study suggest that allocation of restricted feed 2 times a day may alleviate or delay lipotoxicity development and improve reproductive performance in broiler breeder hens.

Effects of feeding level and access to rooting material on behaviour of growing pigs in situations with reduced feeding space and delayed feeding

Seventy-two pigs, housed in groups of four, were allocated to either (1) ad libitum feeding with access to wood chip, (2) restrictive feeding with access to wood chip or (3) restrictive feeding without access to wood chip. The effects of feeding level (treatment 1 vs. 2) and access to wood chip (treatment 2 vs. 3) were investigated in a normal situation, a competitive situation (reduced feeder space) and a conflict situation (delayed feeding). During normal days the pigs without access to wood chip manipulated the floor more, both on a 24 h basis and during the first hour after feed allocation, but the level of manipulating floor in these pigs did not reach the level of manipulating wood chip among pigs on treatment 2. During normal days restrictively fed pigs spent less time feeding on a 24 h basis, but more time feeding during the first hour after feed allocation than ad libitum fed pigs. When feeder space was reduced restrictively fed pigs stood more and were more aggressive during the first hour after feed allocation, but when feeding was delayed restrictively fed pigs were less aggressive during the first hour after normal feeding time. Generally, access to wood chip stimulated explorative behaviour and reduced manipulation of floor and pen mates. However, it had no effect on the response to reduced feeding space or delayed feeding. On the other hand, restrictive feeding increased aggression when feeder space was reduced.

Effects of two levels of feed allocation on IGF‐I concentrations and metabolic parameters in GnRH‐immunized boars

Immunocastration of boars leads to a maintenance of growth harmone (GH) and a loss of anabolic hormones [androgens, oestrogens, insulin-like growth factor (IGF-I)] but an increase of voluntary feed intake. The aim of the experiment was to clarify whether IGF-I is increased by increasing feed supply in immunocastrated boars leading to improved anabolism. Two groups of six boars were given 2 or 3 kg of feed (13.5 MJ ME/kg) daily from 18–28 weeks of age. Because in boars feed intake is limited by gonadal hormones, a group with further increased feed supply could not be included. Until week 22 (second vaccination) gonadal steroids in blood were normal but dropped rapidly thereafter. Growth harmone levels did not change following vaccination. Pigs allocated 3 kg feed had 28% higher circulating IGF-I after the second immunization compared with pigs fed 2 kg feed daily. Higher IGF-I was associated with increased weight gain (682.4 g/day vs. 466.7 g/day; p < 0.01) and protein synthesis ((13)C-leucine infusion; 405 g/day vs. 247 g/day, p < 0.01). Protein breakdown (urea) was not different. Body fat (D(2)O) decreased in the low feed group from 15.2% (week 19) to 6.1% (week 25). In the high feed group it remained at the level found before second vaccination (13.7% vs. 15.0%). It is concluded that in the phase of reduced testicular steroids which inhibit appetite it is possible to increase feed intake which in turn increases IGF-I and protein deposition without accumulating excessive fat.

Effect of an herbal essential oil mixture on growth, laying traits, and egg hatching characteristics of broiler breeders

The effects of supplementing a basal diet with 2 levels of an essential oil mixture and an antibiotic on the growth, laying traits, and egg hatching characteristics of broiler breeders were examined in this study. Nine hundred sixty female and 128 male breeders at an age of 1 d old were randomly allocated to 16 replicates (i.e., 4 replicates of 4 dietary treatments) in a floor pen trial. Two levels of an essential oil mixture (EOM; i.e., 24 and 48 mg of EOM/kg of diet) and an antibiotic (i.e., l0 mg of avilamycin/kg of diet) were added to the basal starter, grower, and laying diets from 0 to 45 wk of age. Daily feed allocations were adjusted to produce a target BW and egg production rate of the breeders throughout the experimental period. The BW of the males and females were determined at 12, 21, and 45 wk of age. Livability during the growing and laying period was not affected by the dietary treatments. The fertility and hatchability of total eggs set were positively affected by the supplementation of the EOM in the diet (P < 0.01). The hen-day egg production, hatching egg weight, settable egg ratio, hatching of fertile eggs, extra large egg rate, and proportion of chick weight to egg weight were not affected significantly. The higher level of EOM (48 mg/kg) added to the diet led to the hatching of the heaviest chickens; the lower level of EOM (24 mg/kg) and antibiotic treatments led to the hatching of the intermediate weight chickens, followed by the control treatment (P < 0.01). Hens given the lower level of EOM in their diets produced a higher number of settable eggs and chicks as compared with those of other treatments, whereas hens fed the control diet yielded the lowest total settable eggs and chicks throughout the experimental laying period (P < 0.05). The results of this study showed that supplementing diets with EOM improved fertility, the hatchability of total eggs set, total settable eggs, total chicks, and the chick weight of broiler breeders.

Allocation of feed based on individual dairy cow live weight changes: I: Feed intake and live weight changes during lactation

Based on individual cow live weight changes, feeding strategies were designed for individual feeding of dairy cows in loose-housing systems and examined in a four-year production trial including 115 Danish Red (DR), 91 Danish Holstein (DH) and 93 Danish Jersey (DJ). Cows were kept in a dairy system based on automatic milking (AMS). The objective was to examine the relationship between feed intake and live weight changes in response to the three feeding strategies examined. All cows were allowed a combination of a mixed ration (MR) and individually separately offered concentrate (ISC) in the AMS. Cows were randomly assigned to one of three feeding strategies; MR1, MR2-E or MR2-L. Cows fed according to the MR1 strategy were allowed one medium energy ration during the whole lactation. Cows on the MR2 strategies were allowed a high energy ration during early lactation, followed by an early (MR2-E) or late (MR2-L) change to a low energy ration. The early and late change was defined as a live weight gain after live weight minimum of 15 and 35 kg respectively for DR/DH and 11 and 25 kg respectively for DJ. Peak energy intake obtained by primiparous cows and cows of DJ was not significantly higher in response to feeding the MR2 strategies. Early reduction (MR2-E strategy) caused a significant longer duration of the total period of mobilization compared to late reduction (MR2-L) within multiparous DR and DH cows. It indicates that early reduction of ration energy concentration forced these cows into a second period of mobilization, whereas cows continued to gain live weight in response to late reduction of ration energy concentration. In general results from the present experiment indicate that feeding according to live weight can be used to manipulate the extent and the duration of the mobilization period especially within multiparous cows. The different results obtained in response to early and late reduction of ration energy concentration suggest that transition from mobilization to deposition conditions is a reversible process only as long as cows are not fully adapted to deposition metabolism. Additionally the results suggest that the transition period from mobilization to deposition is relatively short.

Allocation of feed based on individual dairy cow live weight changes: II: Effect on milk production

Based on individual cow live weight gain, feeding strategies were designed for individual feeding of dairy cows in loose-housing systems, and examined in a four-year production trial including 115 Danish Red (DR), 91 Danish Holstein (DH), and 93 Danish Jersey (DJ). The objective of the present paper was to examine the milk yield obtained in response to three feeding strategies. The interrelationship between feed intake and live weight changes is presented in a companion paper. Cows were stalled in a loose-housing system based on automatic milking, automatic recording of feed intake and automatic weighing of the cows. All cows had 3 kg of individually separately offered concentrate (ISC) in addition to a mixed ration (MR). Cows were either allowed a medium energy MR during whole lactation (strategy MR1) or a high energy MR during early lactation, which was reduced to a low energy MR either early or late (strategy MR2-E and MR2-L). The early and late changes were defined as a live weight gain after live weight minimum at 15 and 35 kg, respectively, for DR/DH and 11 and 25 kg, respectively, for DJ. When MR energy concentration was changed, cows on the MR2 strategies were offered 3 kg per day of extra concentrate. The total allowance of 6 kg ISC was stepwise reduced to 3 kg per day as live weight continued to increase until 50 and 35 kg for DR/DH and DJ, respectively. Compared to feeding the MR1 strategy, the analysis showed that feeding the MR2 strategies did not significantly affect milk yield within primiparous DR and DH or within any DJ, as total lactation feed energy intake within these groups of cows was not significantly affected by the feeding strategy. Results obtained for multiparous DH showed that it is possible to increase milk yield without reducing the milk:feed ratio, when MR2 strategies were applied compared to the MR1 strategy. Feeding high energy rations during early lactation caused a higher peak feed energy intake within multiparous cows of DH and DR, but only multiparous DH obtained higher peak ECM yield in response to higher feed energy intake in early lactation. Across breed the results suggested that cows offered the MR2-E strategy might obtain higher lactation ECM yield compared to cows offered the MR2-L strategy due to a higher ECM yield persistency obtained by cows offered the MR2-E strategy. Results on feed intake and live weight changes presented in a companion paper indicated, that cows offered the MR2 strategies obtained a lower extent of mobilization compared to cows offered the MR1 strategy, and feeding the MR2-E strategy significantly increased duration of the mobilization period, which might have increased MR2-E cows' ability to maintain a high milk production during mid lactation.

Nonlinear mixed models to study metabolizable energy utilization in broiler breeder hens

This study developed mathematical models to overcome limitations of linear models of energy partitioning in hens. The fit of 1 linear and 2 nonlinear models of ME intake (MEI) were compared, using empirical data of 288 caged broiler breeder hens from 20 to 60 wk of age. Pullets were individually caged at 16 wk and assigned to 1 of 4 feed allocation groups. Three groups had feed allocated on a group basis with divergent target BW: standard (STD), HIGH (STD x 1.1), and LOW (STD x 0.9). The fourth group had individual-based feed allocation (IND) and followed the STD BW target. The linear model expressed MEI as a function of BW(0.75), ADG, egg mass (EM), and temperature. Nonlinear mixed models employed a normally distributed term associated with hen metabolic BW, and exponential terms of ADG and EM, or Cobb-Douglas form interactions between terms. Fit was evaluated with the Bayesian information criterion and systematic bias was analyzed through linear regressions of observed versus expected values. The linear model estimated energy partitioned to maintenance and retention in the range of reported values in the literature. However, this model had the poorest fit (R(2) = 0.64) and exhibited a slope bias of 0.91 (i.e., MEI was overestimated at low values and underestimated at high values). The first nonlinear mixed model indicated that MEI partitioned to ADG was a factor of ADG(1.15), whereas the ME partitioned to EM was a factor of EM(1.12). This model had improved fit (R(2) = 0.71) relative to the linear model. The second nonlinear mixed model indicated that the energy requirement for ADG increased by 0.60% and the EM energy requirement decreased by 2.07% for each 1% increment in BW. This model further improved fit (R(2) = 0.75). Nonlinear mixed models reduced estimation bias by accounting for individual variation in maintenance energy expenditure. These nonlinear mixed models may be used to analyze energy partitioning in animals, to develop prediction equations of MEI, to evaluate individual efficiency for maintenance, and to assess diets regarding the slope of bias in coefficients of maintenance energy requirements.

The Effect of Different Feed Restriction Programs and Dietary L-Carnitine Supplementation on Reproductive Performance, Efficiency, Frame Size and Uniformity in Broiler Breeder Hens

Two experiments were conducted to determine the effect of Everyday (ED) or Skip-a-day (SK) feed restriction programs and L-carnitine supplementation on breeder reproductive performance. In Experiment 1 a 2 x 2 factorial design was used to compare feeding regimens (ED vs. SK) and L-carnitine supplementation (0 vs 50 mg /kg). L-carnitine supplementation began at day 1 and lasted throughout the 45 week experimental period. SK feeding programs were implemented from 28 days of age to 5% production. Feed allocation was adjusted to ensure equal BW between groups. At 21 weeks, 60 pullets from each treatment combination were housed individually. Feeding ED improved the feed conversion ratio by 0.2 4 units for 21 week pullets, resulted in 3 days earlier attainment of Sexual Maturity (SM), produced 4.6 more total eggs and 5.0 more settable eggs than SK fed pullets. Uniformity was less for ED fed pullets (2.07 higher CV). Egg size was increased by 1.16g with dietary L-carnitine. Body composition was not affected by either feeding regimen or L-carnitine. In Experiment 2, the same effects were tested but a low density grower diet was used from 4-18 weeks. L-carnitine was supplemented from day 1 and SK programs began at day 28 and extended to 5% production. Feed allocation was adjusted to maintain equal BW and 80 pullets per treatment were individually housed at 21 weeks. L-carnitine and ED feeding through 21 wk improved the FCR by 0.06 and 0.12 units, respectively. Feeding ED resulted in 5.8 days earlier SM, 4.7 more total eggs and 4.4 more settable eggs than SK. Uniformity was not affected by feeding regimen or L-carnitine. Carcass fat was reduced and carcass ash was increased by L-carnitine supplementation at 22 weeks. It was concluded that ED fed breeders are more productive than SK fed breeders primarily because of earlier SM. ED fed breeders are more efficient than SK breeder pullets because there are less nutrients wasted for tissue replenishment. Feeding breeder pullets ED with low energy density diets helped eliminate uniformity differences for pullets fed ED and SK feeding regimens. Breeders fed L-carnitine during 21 wk rearing period improved the FCR by 0.06 units for both Experiment 1 and 2. While, the effect of L-carnitine on total egg production was not significant, L-carnitine supplemented birds produced 3.9 and 2.7 more total eggs at 45 weeks than non- supplemented birds in Experiments 1 and 2 respectively. The consistency of the results and the associated p-values (p = 0.12; p = 0.13) for total egg production in the two experiments suggest that L-carnitine may have some beneficial effects on egg production. Breeders fed carnitine also showed significant increases in EW in Experiment 1 and near significant (p = 0.13) increases in EW for the second experiment. Carnitine was unable to attenuate the negative effects of SK feeding associated with the lengthy fasting periods.

Effect of reducing body weight variability on the sexual maturation and reproductive performance of broiler breeder females

A study was performed to assess the effect of reducing BW variability on sexual maturation and reproductive performance of broiler breeder hens. A total of 208 Ross 708 1-d-old pullets were randomly assigned at hatch to 1 of 2 feed allocation treatments starting at 16 wk of age when all birds were placed in individual cages. A control treatment had feed allocated on a group basis (GRP) and followed the recommended BW target. A second treatment had feed allocated on an individual bird basis (IND). By design, the BW of IND pullets converged at 20 wk. This design dictated that IND birds had a lower BW variability and a higher feed intake variability than GRP birds. Pullets were retrospectively classified into 3 initial (16 wk) BW categories: low, average, or high, using the mean ± 0.5 SD as threshold. After their first egg, 64 birds were killed and dissected for determination of fleshing, fatness, and reproductive morphology. Egg production traits were analyzed to 60 wk, when the remaining birds were killed and dissected. Reducing BW variability did not reduce variability of age, follicle numbers, and ovary and oviduct weight at sexual maturity. The IND feed allocation accelerated the onset of production of low BW birds, which increased total egg production (177 eggs) and average sequence length (3.9 d) with respect to GRP × low birds (163 eggs; 3.0 d). However, IND × low hens produced more eggs <52 g than GRP × low hens (22 versus 8 eggs). The IND treatment increased variability of ovary weight, large yellow follicle number, and large yellow follicle weight at 60 wk. Reducing BW variability increased variation in ovarian morphology at the end of production, which suggests that optimal BW for reproduction varied among birds. Correcting BW from 16 wk to reach the BW target primarily affected low initial BW pullets, which entered lay sooner and produced more eggs, although 91% of the additional eggs weighed <52 g.

Characterization of energetic efficiency in adult broiler breeder hens

This trial characterized residual feed intake (RFI) and residual maintenance requirement (RME(m)) as measures of energetic efficiency in broiler breeder hens. The RFI was defined as the difference between observed and expected ME intake and RME(m) as the difference between observed and expected maintenance requirements. A total of 600 Ross 708 1-d-old pullets were placed in floor pens. At 16 wk, 144 hens were caged and randomly assigned to 1 of 2 feed allocation treatments (72 birds each). The control treatment had feed allocated on a group basis (GRP) following the standard BW target. A second treatment had feed allocated on an individual-bird basis (IND) and followed the same BW target as GRP. Sexual maturity age, egg and chick production, and several feed conversion ratios were correlated to standardized efficiency indices of RFI (SRFI) and RME(m) (SRME(m)) in each treatment. Greater SRFI and SRME(m) values described a greater energetic efficiency. Residual feed intake was more variable in IND than GRP hens (P < 0.001). The variability of RME(m) did not differ between treatments (P = 0.14). The SRFI was positively correlated to egg production in the GRP hens (r = 0.31), but negatively correlated in IND hens (r = -0.40) and was correlated to feed conversion per chick only in the GRP-based feed allocation (r = -0.44). The SRME(m) correlated strongly to egg production (r = 0.64), chick production (r = 0.64), and feed conversion per chick (r = -0.59) in both feed allocation treatments. Feed intake confounded the RFI calculation, which limits the value of RFI as a selection criterion in meat-producing animals. The independence of RME(m) from feed intake is desirable for energetic efficiency assessment in selection programs because consistent values can be obtained across different management schemes. Hens with lower maintenance requirements (greater RME(m) efficiency) partitioned more energy toward reproduction than did high-maintenance hens. The RME(m) methodology provided an unbiased estimate of energetic efficiency by adjusting the maintenance requirement for the effect of dietary thermogenesis.

Effects of maternal energetic efficiency on egg traits, chick traits, broiler growth, yield, and meat quality

This study assessed egg traits, chick traits, growth, yield, and meat quality characteristics of the offspring from broiler breeders classified by 2 measurements of energetic efficiency: residual feed intake (RFI), defined as the difference between observed and expected ME intake, and residual maintenance requirement (RME(m)), defined as the residual of the relationship between hen maintenance requirement and feed intake. A group of 72 pullets were placed in laying cages from 16 to 60 wk of age. Individual hen-based feed allocation was provided following a standard BW target. At 41wk, eggs from 8 d of production were collected and pedigree hatched. Chicks were assigned to 1 of 3 maternal RFI (RFI(mat)) categories: low, average, and high. A total of 366 chicks were placed in 36 floor pens, 6 per sex x RFI(mat) interaction, and raised to 38 d. At the end of the breeder experiment (60 wk), broilers were retrospectively assigned to a low or high maternal RME(m) (RME(mmat)) category. Low RFI(mat) broilers had greater 38-d BW than average and high RFI(mat) broilers. That was achieved through a greater BW gain and feed intake of low RFI(mat) broilers from 21 to 28 d. It was found that RFI(mat) had no effect on feed conversion, yield, or meat quality characteristics. Low RME(m) hens produced heavier eggs (62.3 g) and chicks (42.5 g) than high RME(m) hens (60.0 g; 41.0 g), but RME(mmat) did not affect broiler 38-d BW. High RME(mmat) broilers had greater breast yield (29.5%) and lower breast shear force (4.7 kg of force/g) than low RME(mmat) broilers (28.5%; 5.6 kg of force/g). The low RFI(mat) x high RME(mmat) broilers had the greatest growth to 38 d. It was found that RFI(mat) was inversely related to broiler growth, particularly when RME(mmat) was high. Although low maintenance requirements may be desirable for egg and chick production, hens with a high maintenance requirement produced broilers with greater breast yield and tenderness. Minimizing maintenance requirements may not be compatible with maximizing broiler performance and meat yield.

Effect of Initial Full Feeding of Broiler Breeder Pullets on Carcass Development and Body Weight Variation

Broiler breeder pullets are fully fed for several weeks to give chicks a vigorous start, to establish an adequate frame size, and to build increased flock BW uniformity. This study was designed to determine whether reducing the length of the initial ad libitum feeding period of pullets would be detrimental to subsequent fleshing, skeletal development, and BW variation. A total of 720 Ross 308 pullets were placed in 8 pens on the day of hatch and provided ad libitum access to feed at 1 wk (1WK) or 3 wk (3WK) of age, at which time a 5:2 restriction program began. Individual BW and external fleshing scores, and flock BW variation (CV and uniformity) were monitored. At 4, 8, 12, and 16 wk, 60 randomly selected birds per treatment were dissected for assessment of breast muscle, fatness, and reproductive development. At 3 wk of age, BW of the 3WK pullets (471 g) was greater than that of the 1WK pullets (312 g), and the daily rate of gain was double. Although feed allocation was decreased markedly at 3 wk in 3WK birds, by 4 wk they weighed 30% more, and had a greater frame size and proportion of breast muscle than the 1WK birds. At 8 wk of age, the 3WK birds were still heavier (973 g for 3WK vs. 899 g for 1WK). Most carcass measures were similar between treatments at 12 wk of age, by which time BW profiles were similar. At 16 wk of age, frame size and proportion of breast muscle were not different between groups. The BW variation did not differ through the initial 12 wk, but was superior at 14 and 16 wk of age in 1WK birds, possibly because of greater feed allocation between 8 to 16 wk, which is the most intense feed restriction period. The reduced feed intake of 3WK birds at the onset of feed restriction reduced their ME requirement for maintenance, likely contributing to this result. Increasing the length of the ad libitum feed access period after hatch altered growth and conformation traits to 8 wk of age and did not affect frame size or proportion of breast muscle, but increased BW variability late in the rearing period.

Diet selection and eating behaviour of lactating goats subjected to time restricted feeding in choice and single feeding system

This study was carried out to investigate diet selection and eating behaviour of lactating German Fawn × Hair Crossbred goats in different feeding methods and levels. Twenty German Fawn × Hair first backcross does (B 1) were allocated into 4 treatment groups (2 feeding methods single (TMR) and choice feeding × 2 feeding levels ad libitum and restricted) with 5 replicates. Restricted feeding was applied only 4 h feed allocation during day. Barley, corn, soybean meal, corn gluten meal, wheat bran and alfalfa hay were feed ingredients for single and choice feeding. Eating patterns, milk yield and composition were determined for 8 weeks. The following results were obtained: (1) the meal criteria for goats restricted single and choice-fed, ad libitum single and choice-fed were determined as 1.00 and 0.63, 12.88 and 10.23 min, respectively. (2) Ad libitum feeding increased meal size, meal length, intermeal interval, total eating duration and decreased eating rate and meal number, compared to restricted feeding ( P < 0.01). Choice feeding decreased meal size ( P < 0.05), meal length ( P < 0.01) and increased eating rate and meal number ( P < 0.01), compared to single feeding. Restricted fed goats decreased intermeal interval in single feeding compared to choice feeding ( P < 0.01), but increased meal number in choice feeding ( P < 0.01). (3) Ad libitum choice-fed does made a diet containing 12.79% corn, 35.41% barley, 13.21% wheat bran, 5.35% soybean meal, 1.28% corn gluten meal and 29.80% alfalfa meal while restricted choice-fed does made a diet having more corn (27.69%), corn gluten meal (5.62%) and wheat bran (16.17%) and less barley (14.37%) and soybean meal (4.51%). (4) Choice feeding decreased RUP intake ( P < 0.05) without affecting milk protein, irrespective to feeding levels, while having a tendency to increase in milk yield (14.2%) and 4% FCM (8.8%). (5) Restricted feeding decreased DM, ME, ADF and NDF intakes ( P < 0.05) with concomitant decreases in 4% FCM, total milk solid, ash and fat compositions ( P < 0.05), irrespective to feeding methods. (6) Choice-fed goats changed their preferences for a possible synchronized nutrient intake during a daytime, as sorted barley, soybean meal and alfalfa hay from early morning to late afternoon. It could be concluded that choice-fed goats have the ability to make their diet to meet nutrient requirements and had a tendency to increase in milk yield. Restriction in feeding time resulted in lower feed intake and milk yield, although the animal changed their feed preference in favour of high quality ingredients and eating pattern with lower meal criterion and intermeal interval.

Feeding Broiler Breeder Males. 4. Deficient Feed Allocation Reduces Fertility and Broiler Progeny Body Weight

Two experiments were conducted to evaluate the effects of male broiler breeder feed intake on broiler progeny performance. In experiment 1, a low cumulative nutrition program supplied 29,580 kcal of ME and 1,470 g of CP, whereas a high cumulative nutrition program supplied 33,500 kcal of ME and 1,730 g of CP to photostimulation at 21 wk of age. Two diets (HiDiet and LoDiet) were formulated, and a single feeding program was used to achieve the selected nutrient intakes. The HiDiet group of males in experiment 1 achieved greater BW and exhibited lower fertility when fed as the LoDiet males from the onset of egg production. The HiDiet breeder males subsequently produced male broilers from eggs laid at 29 wk of age that exhibited lower BW at 42 d. This was due to the heaviest 50% of the breeder males in this treatment not gaining BW consistently due to less-than-adequate ME intake relative to their greater BW requirements. Two feeding programs during the production period (constant or increasing) were compared in experiment 2. Broilers were hatched from eggs laid at 32 and 48 wk of age to evaluate the vertical effect of male treatments on progeny performance. No difference in fertility or broiler performance was found at 32 wk. However, the constant feeding program produced lower fertility from 36 to 55 wk of age, and this resulted in a lower male and female broiler progeny BW at 42 d of age from eggs collected at 48 wk of age. Adequate breeder male feed allocation during the production period improved fertility and favorably affected broiler progeny performance in both experiments. However, broiler progeny effects were observed only when there were differences in fertility, which suggests that the males with the greatest genetic potential were not mating at these times.