Dietary Energy Levels Research Articles

Effect of β-Mannanase Supplementation on Growth Performance, Ileal Digestibility, Carcass Traits, Intestinal Morphology, and Meat Quality in Broilers Fed Low-ME Diets.

Simple Summaryβ-mannans, an example of non-starch polysaccharides, is one of the important anti-nutritional factors found in many leguminous feedstuffs used as raw material in poultry feed formulation. β-mannans bind to nutrients, reduce their bioavailability, and also increase the viscosity of intestinal digesta, which prevents the proper mixing of enzymes with digesta and affects the digestibility of nutrients. All these conditions ultimately reduce the growth performance of poultry birds. So, the objective of present study was to lower the effect of β-mannans by using β-mannanase in broiler diets. Results suggested that β-mannanase supplementation improved the intestinal morphology, which helped to increase the dry matter and crude fiber digestibility in broilers fed low energy diets. In addition, growth performance of broilers was not affected by reducing dietary energy levels with added β-mannanase than the Control group. Similarly, carcass traits were not affected by decreasing dietary energy levels with supplementation of β-mannanase. In conclusion, it could be stated that a low caloric diet with added β-mannanase had no negative effect on growth performance and carcass characteristics; however, it improved the dry matter and crude fiber digestibility.Experiment was designed to analyze the effect of low caloric diets, supplemented with β-mannanase on growth performance, carcass characteristics, nutrient digestibility, and other parameters in broilers. In this study, 400 broiler chicks were randomly divided into four treatments (Cont: without β-mannanase; LM-30, MM-60, and HM-90: supplemented with 200, 400, and 600 mg/kg β-mannanase, respectively). Dietary metabolizable energy (ME) in Cont was standard (starter diet 3100 kcal/kg; finisher diet 3200 kcal/kg) and reduced by 30, 60, and 90 kcal/kg, correspondingly in β-mannanase-supplemented treatments. The results exhibited that growth performance was not affected by reducing dietary energy levels with supplementation of β-mannanase. Ileal digestibility of DM and CF was improved (p < 0.01) by supplementation of β-mannanase at low dietary ME levels. Concerning carcass traits, the relative weight of breast meat, drumstick, and abdominal fat increased (p < 0.05) with β-mannanase supplementation in low-ME diets. Treatment HM-90 showed significantly (p < 0.05) better results regarding villus height and VH:CD. It could be concluded from the present results that supplementation of β-mannanase could improve the nutrient digestibility so that it is possible to reduce the dietary energy level without compromising production performance, carcass trails, and meat quality in broilers.

Effects of Different Energy Levels on the Milk Performance and Blood Chemistry in Jersey Cows in Tibet

Background: Owing to the extreme cold and hight elevation, demand for fat by people in the plateau is great than those on the plains Butter were used to supply of fat to the herders in areas as remote as rural Tibet and as one of the traditional food, it occupied an importan place in the diet. Therefore, there is a significance in improving butter production in Tibet. Methods: To explore the effects of energy levels on milk performance, blood chemstryand milk hydrolysis amino acid in Jersey cows in Tibet. Forty late-lactation Jersey cows were randomly assigned into 4 groups equally according to the level of energy: E1 (11.50 MJ/kg); E2 (12.0 MJ/kg); E3 (12.5 MJ/kg) and E4 (13.0 MJ/kg). Result: The results indicated milk yield, milk fat content, total soilds content, lactose contentand soilds-not-fat content increased in response to higher levels of dietary energy, whereas the greater (P less than 0.0001) value of milk protein content was observed at the lower levels of dietary energy. The greater plasma GPT content was obtained in group E4 (P less than 0.0001), whereas, the greater plasma TG and GLU were observed in group E3 (P less than 0.01). Plasma TG and LDH of group E2 were greater than those of another treatments (P less than 0.0001) and the plasma UN of group E1 was significant higher among treatments (P less than 0.0001). The greater values of most hydrolysis amino acid and total AA in milk were observed at the lower level of group E1.

Effect of Exogenous Enzymes Cocktail on Performance, Carcass Traits, Biochemical Metabolites, Intestinal Morphology, and Nutrient Digestibility of Broilers Fed Normal and Low-Energy Corn-Soybean Diets.

Simple SummaryCorn and soybean meal (SBM) are the principal sources of energy and protein in poultry feed, respectively. Decreasing feed cost per unit of production and increasing the nutritional value of feed ingredients like corn and SBM are continuous concerns for poultry producers. Corn and SBM-based diets are incompletely digested by poultry due to the presence of non-starch polysaccharides (NSPs), which can obstruct the processes of nutrient digestion and absorption. Poultry does not own endogenous enzymes capable of digesting NSPs. The use of enzyme cocktails (EC) and dietary energy sources are essential topics in the poultry industry because they could enhance nutrient utilization by reducing the harmful effects of NSPs. Therefore, evaluating the efficacy of EC that may improve the feeding value of corn–SBM diets warrants attention. The efficacy of two doses of an EC with multiple enzymatic activities at two levels of dietary metabolizable energy (ME) on the performance of broilers fed corn and SBM-based diets up to 35 days was evaluated. Our results indicate that adequately adjusting dietary ME and using the EC with xylanases, β-glucanases, cellulases, proteases, pectinases, and debranching enzymes activities could enhance the nitrogen-corrected apparent ME of corn and SBMbased diets for broiler chickens and potentially offer economic advantages to producers.Ross 308 broilers in a randomized complete block design with a 2 × 2 factorial treatment arrangement (four treatments with 12 replications of six chicks each) were fed corn and SBMbased diets with two concentrations of metabolizable energy (ME) (normal (positive control, PC) and low (negative control, NC)) and two amounts of enzyme cocktail (EC) (0% and 0.005%) for 35 days. Performance, carcass traits, serum metabolites, ileal histology, and apparent nutrient digestibility were evaluated. Compared with the non-supplemented diet, the use of EC improved feed conversion ratio (FCR) over 26–35 and 0–35 days (p < 0.01), European performance efficiency factor (EPEF) over 26–35 days (p < 0.05), dressing yield (p < 0.01), villus height (p < 0.05), nitrogen-corrected apparent ME (AMEn) (p < 0.01), and serum glucose (p < 0.05). Compared with the NC diet, feeding the PC diet improved FCR over all experimental periods (p < 0.01, p < 0.05, p < 0.05, and p < 0.01, respectively), EPEF over 0–10 days (p < 0.05), and AMEn retention (p < 0.01). To conclude, the AMEn of broilers fed corn and SBM diets could be improved by adequately adjusting dietary ME and using a cocktail of non-starch polysaccharide-degrading enzymes, improving commercial benefits to producers.

PSVI-2 Effect of Increasing the SID Tryptophan:Lysine Ratio and Dietary Energy Level on Growth Performance of Growing-Finishing Pigs

Abstract The objective of this study was to evaluate the effect of increasing the SID Tryptophan:Lysine ratio in growing-finishing and dietary energy level in finishing on growth performance of growing-finishing pigs (43.6 ± 0.85 kg to 131.7 ± 2.09 kg BW). A RCBD was used with a 2 × 2 factorial arrangement of treatments: A) Dietary Energy Level: Low Energy (3,294 kcal/kg ME) vs. High Energy (3,527 kcal/kg ME) and B) SID Tryptophan:Lysine Ratio: Low Try:Lys [16%] vs. High Try:Lys [21%]. Dietary Energy Level treatment was applied from 96 kg BW to end of study and SID Tryptophan:Lysine Ratio treatment was applied throughout the study period. Diets were based on corn-soybean meal and corn coproducts and formulated to meet or exceed the nutrient requirements (NRC, 2012) for each of 4 dietary phases. A total of 1,356 pigs were housed in single-sex groups of 34 pigs (10 replicates) at a floor space of 0.63 m2/pig. Pigs had ad libitum access to feed and water. Pen was the experimental unit and data were analyzed using R version 4.0.2, with the model accounting for the fixed effects of treatment, the interaction, and the random effect of replicate. There were no treatment interactions (P &amp;gt; 0.05). High Try:Lys compared with Low Try:Lys increased (P &amp;lt; 0.05) overall ADG but had no effect (P &amp;gt; 0.05) on ADFI or G:F (Table 1). The High Energy treatment reduced (P &amp;lt; 0.05) overall ADFI and increased (P &amp;lt; 0.05) overall G:F compared with the Low Energy treatment. In summary, pigs fed the elevated SID Tryptophan:Lysine level had increased ADG and feeding a diet with a higher dietary energy level improved feed efficiency.

105 The Impact of Lowering Floor Space Allowance and Dietary Energy Level on Finishing Pigs, from 65 Kg to Market, on Growth Performance

Abstract The objective of this experiment was to evaluate the impact of reducing floor space allowance in finishing hogs with a starting body weight (BW) of 65 ± 2 kg when fed high versus low energy diets on growth performance. Mixed-sex pens (n=88) with 24 ± 1 pigs per pen were blocked by starting BW to a randomized complete block design with eight treatments. These eight treatments formed a 2 x 4 factorial arrangement with 2 energy levels: low (LE, 3270 ±19 kcal/kg ME) vs. high (HE, 3392 ±19 kcal/kg ME) accomplished through fat inclusion; and 4 floor space allowances: 0.60, 0.63, 0.65, 0.67 m2 per pig. Assigned floor space was adjusted by moveable gates in the rear of the pen, which were corrected at each pig removal until the marketing phase. Pen weight and feed disappearance were measured for 2 phases at d 0, 29, and 48 to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (GF). Data were analyzed by pen (SAS 9.4, Cary, NC) with the repeated measure of phase, and the fixed effects of floor space allowance, dietary energy, and the interaction between. For the overall trial, decreased floor space had no effect (P &amp;gt; 0.1) on ADG, ADFI, or GF (0.36, for all). Energy had a significant effect (P &amp;lt; 0.01) on ADFI (3.17 vs 3.12 kg for LE and HE, respectively) and GF (0.35 and 0.36 for LE and HE, respectively), and tended to impact ADG (1.12 vs 1.13 kg, for LE and HE, respectively; P = 0.08). In conclusion, lowering floor space allowance from 0.67 m2 down to 0.60 m2 did not affect the growth performance of pigs starting at 65 kg. Pigs fed HE diets had 2.86% better GF compared with pigs fed LE diets, however had similar growth and body weight.

Managing broiler production challenges at high altitude.

This review covers the challenges of broiler chickens at high altitude, with the focus on growth performance and physiological response. The review also sheds light on nutritional and management interventions that help overcome the challenges raised at high altitude. Reduced concentration of atmospheric oxygen is by far the biggest challenge that remarkably affect growth performance and livability of broiler chickens reared in high altitude area. Broiler chickens have endured intensive genetic selection, which potentially predispose them to several metabolic disorders. Hypoxia is an overriding factor that may increase the incidence of metabolic disorders, mainly ascites syndrome at high altitude. Commercial broiler strains cannot fully achieve their genetic potential when raising at highland regions. Careful nutrition and management considerations are required to prevent metabolic disorders when raising broilers at high altitude. In ovo or in‐feed nutraceuticals such as l‐carnitine and guanidinoacetic acid as well as pharmaceuticals, texture of feed and the use of proper sources and levels of dietary energy and protein are important factors that need to be carefully considered for rearing broiler chickens at high altitude. Management strategies such as lighting programs have been shown to be effective to circumvent ascites prevalence. Special breeding programs may also be considered to develop strains with resistance to ascites.

Energy Values of Corn and Rice Bran and Energy Levels for Ducks – Basis in Establishing Energy Requirement for Improved Philippine Mallard Duck

New breeds of Philippine Mallard Ducks (PMD) were developed to ensure the availability of outstanding stocks for egg production. Maximizing the potentials of these new breeds can be achieved with sound nutrition. Energy is considered the most important and occupy big fraction in the diet of duck as it influences feed intake and proportion of other nutrients in the diet. Optimaldietary energy levels for the new breeds of PMD is yet to be established.. Determining the energy values of common and locally abundant basal feeds such as corn and rice bran for PMDwill serve as a basis in the inclusion of these feeds to duck’s diet. Ducks are considered more efficient in maximizing the energy values of corn (CO) and rice bran (RB) despite of the large proportion of non-starch polysaccharides of RB compared to chickens. Dietary energy levels have not been established for PMD unlike in Pekin ducks (PD) and some indigenous or country ducks. Fast growing PD tend to require a denser energy ranging from 3008 to 3284 kcal/kg compared to 2700 to 2950 kcal/kg for indigenous breeds and khaki Campbell (KC) for optimal performance. It has been found out that the PMD is closely more related to KC than PD. Hence, the possibility of requiring a lower dietary energy than PD. The determination of energy values of CO and RB for PMD and establishment of optimal dietary energy level will facilitate the formulation of PMD specific diet. Thus, this condensed information will serve as concrete viewpoints in understanding bioenergetic dynamics of PMD.

Effects of different energy diets on DNA methylation and mRNA expression in follicle stimulating hormone receptor gene promoter region of Duolang sheep during estrus.

The aim of this study was to study the relationship between the methylation level of the promoter region of follicle-stimulating hormone receptor (FSHR) gene and the mRNA expression of Duolang sheep fed different energy diets. In this study, polyembryo estrus Duolang sheep under different energy levels were selected as the experimental subjects. Dietary nutrient level reference (NY/T 816-2004), medium energy level was 10.88MJ/day, high and low energy groups were increased and decreased by 15% on the basis of medium energy level, respectively 12.51MJ/day, 9.25MJ/day. Through RNA and DNA extraction, qPCR, bisulfitegenomicse-quencing PCR (BSP), sequence matching and other analysis of ovarian tissue of Duolang sheep. The difference of DNA methylation level and mRNA expression of FSHR gene during estrus in Duolang sheep fed with different energy diets was detected. The results showed the expression level of FSHR in high energy group was significantly higher than that in low energy group (P < 0.01), the expression level of FSHR in high energy group was significantly higher than that in medium energy group (P < 0.05), and the expression level of FSHR in medium energy group was significantly higher than that in low energy group (P < 0.05). In the target fragment of the promoter region of the FSHR gene, the methylation rate was 25% in the high energy group, 50% in the normal group, and 75% in the low energy group. This study revealed that different dietary energy levels had certain effects on the FSHR gene DNA methylation level and mRNA expression, and the expression level was negatively correlated with methylation level.

Dietary energy influences ovarian morphology and in vitro maturation of oocytes in goats

ABSTRACT The present study aimed to determine the effects of dietary energy levels on follicular development and in vitro maturation of oocytes in pre-pubertal goats. Thirty-six female six-month-old stall-fed Black Bengal goats were divided into three equal groups that were randomly assigned to receive three iso-nitrogenous diets containing different levels of metabolizable energy (8.67, 10.20, and 11.73 MJ/kg DM). After 150 days of rearing, the weight, length and width of the ovaries increased significantly in medium and high levels of dietary energy groups than in the low-energy group. Medium and high-energy levels in the diet significantly increased the number of visible antral follicles and large antral follicles than the low level of dietary energy. The number of antral follicles per ovary was higher in high-energy fed goats than medium- and low-energy groups. The low-energy group showed more non-growing primordial follicles and degenerated follicles than the other groups. The medium- and high-dietary energy levels significantly increased the maturation rate of oocytes to metaphase II than the low-energy group. These results reveal that the level of dietary energy positively influences follicular development and meiotic competence of goat oocytes.

Effect of diet energy level and genomic residual feed intake on bred Holstein dairy heifer growth and feed efficiency

The objective of this study was to determine growth, feed intake, and feed efficiency of postbred dairy heifers with different genomic residual feed intake (RFI) predicted as a lactating cow when offered diets differing in energy density. Postbred Holstein heifers (n = 128, ages 14-20 mo) were blocked by initial weight (high, medium-high, medium-low, and low) with 32 heifers per block. Each weight block was sorted by RFI (high or low) to obtain 2 pens of heifers with high and low genomically predicted RFI within each block (8 heifers per pen). Low RFI heifers were expected to have greater feed efficiency than high RFI heifers. Dietary treatments consisted of a higher energy control diet based on corn silage and alfalfa haylage [HE; 62.7% total digestible nutrients, 11.8% crude protein, and 45.6% neutral detergent fiber; dry matter (DM) basis], and a lower energy diet diluted with straw (LE; 57.0% total digestible nutrients, 11.7% crude protein, and 50.1% neutral detergent fiber; DM basis). Each pen within a block was randomly allocated a diet treatment to obtain a 2 × 2 factorial arrangement (2 RFI levels and 2 dietary energy levels). Diets were offered in a 120-d trial. Dry matter intake by heifers was affected by diet (11.0 vs. 10.0 kg/d for HE and LE, respectively) but not by RFI or the interaction of RFI and diet. Daily gain was affected by the interaction of RFI and diet, with low RFI heifers gaining more than high RFI heifers when fed LE (0.94 vs. 0.85 kg/d for low and high RFI, respectively), but no difference for RFI groups when fed HE (1.16 vs. 1.19 kg/d for low and high RFI, respectively). Respective feed efficiencies were improved for low RFI compared with high RFI heifers when fed LE (10.6 vs. 11.8 kg of feed DM/kg of gain), but no effect of RFI was found when fed HE (9.4 vs. 9.5 kg of DM/kg of gain for high and low RFI, respectively). No effect of RFI or diet on first-lactation performance through 150 DIM was observed. Based on these results, the feed efficiency of heifers having different genomic RFI may be dependent on diet energy level, whereby low RFI heifers utilized the LE diet more efficiently. The higher fiber straw (LE) diet controlled intake and maintained more desirable heifer weight gains. This suggests that selection for improved RFI in lactating cows may improve feed efficiency in growing heifers when fed to meet growth goals of 0.9 to 1.0 kg of gain/d.

Effects of age at first breeding and dietary energy levels during the rearing period of replacement gilts on reproductive performance

Context The occurrence of second parity syndrome is a major reason for culling sows depending on the bodyweight and energy level balance during the first lactation. Equally, the nutrition of gilts during the rearing period influences the age of first oestrus, longevity and reproductive performance. Aims The experiment investigated: (1) the influence of gilt mating age (early [EL], middle [MD] and late [LT]) at the first parity on reproductive performance, and (2) the interaction between dietary energy levels (high, 3320 kcal/kg; low, 3120 kcal/kg) and mating age. Methods A total of 120 crossbred (Duroc × Landrace × Yorkshire) gilts were allotted to six treatments according to a 3 × 2 factorial arrangement based on mating age (EL [222 days], MD [244 days] and LT [264 days]) at the first parity and dietary energy levels (high, 3320 kcal/kg; low, 3120 kcal/kg). The average weight of gilts were 141 ± 3, 153 ± 3 and 164 ± 3 for the EL, MD and LT groups, respectively. Results High-energy diets tended to increase the growth rate of gilts (P = 0.083). At insemination, bodyweight and back-fat thickness were higher (P &lt; 0.05) in the LT group. Back-fat thickness at farrowing was lower (P &lt; 0.05) in the EL group. The back-fat thickness loss during lactation was highest in the LT group (P &lt; 0.05) during parity one and two. Feed intake during lactation was significantly reduced (P &lt; 0.05) in the LT gilts in parity one. Insemination age and dietary energy levels had no significant effects on, litter size, litter weight and weaning to oestrus interval. A higher blood insulin-like growth factor (P &lt; 0.05) was observed in the EL gilts during the first service and weaning. Conclusion Based on these findings, early inseminated gilts had a lower bodyweight loss during lactation without affecting litter size or growth, which in the long term may positively impact culling age. Implication This information may guide swine farmers on the most appropriate age to breed gilts at first service for increased reproductive life. The provision of high-energy feeds did not translate into any meaningful interaction towards improving reproductive performance in gilts.

Dietary net energy mainly affects growth performance and pork quality of finishing pigs

The present study was carried out to evaluate the effect of net energy levels in diets for barrows, from 70 to 100 kg, on performance, plasma parameters and carcass characteristics. Two experiments were carried out: in the first (Experiment I), a metabolism assay was carried out to estimate the net energy (NE) of experimental diets. Twelve crossbred barrows, averaging 85.74 ± 6.80 kg initial body weight, were distributed in a randomized block design with two metabolizable energy (ME) levels (3100 and 3500 kcal kg–1) with six replicates and one animal per experimental unit. In the second (Experiment II), 45 castrated male pigs were used, averaging 70.10 ± 1.26 kg of initial body weight distributed in a randomized block design, with five NE levels (2345, 2425, 2505, 2585, 2665 kcal kg–1), nine replicates and one animal per experimental unit. The increase in diet NE levels provided a linear reduction (p ≤ 0.00039) in average daily feed intake (ADFI). There was a quadratic effect on NE efficiency (p ≤ 0.0027), average daily gain (ADG), (p ≤ 0.0352) and the feed:gain ratio (F:G), (p ≤ 0.0024), the optimal levels being estimated at 2485, 2493 and 2533 kcal kg–1, respectively. Drip loss (DL) decreased (p ≤ 0.0001) as NE levels increased. There was also a linear decrease (p ≤ 0.0462) in the Minolta color parameter (+a*), due to the NE levels. Plasma parameters were not affected (p > 0.05) by NE levels. The dietary net energy levels affected the performance and meat quality of finishing pigs and the level of 2493 kcal kg–1 provided the best ADG.

Dietary net energy levels for growing barrows from 30 to 70 kg

ABSTRACT: This study evaluated the effect of dietary net energy (NE) levels on growth performance and carcass characteristics of barrows from 30 to 70 kg of body weight (BW). Sixty barrows with initial body weight (IBW) of 31.94 ± 3.54 kg and final body weight (FBW) of 71.98 ± 5.99 kg were allotted to one of five dietary NE levels (2.40, 2.45, 2.50, 2.55, and 2.60 Mcal kg-1), using a completely randomized block design with six replicates and two barrows per replicate. The experimental period was divided into phase I: 30 to 50 kg and phase II: 50 to 70 kg. The variables analyzed were average daily feed intake (ADFI), net energy intake (NEI), digestible lysine intake (LysI), average daily gain (ADG), feed conversion (FC), FBW, digestible lysine conversion:gain (LysI:G), Cost:Gain (C:G), loin eye area (LEA), muscle depth (MD), first backfat layer (BF1), second backfat layer (BF2), total backfat (BFt), lean meat percentage, and carcass bonus index (BI). In phase I, there was a linear increase (P &lt; 0.05) in FBW, ADG, NEI, and LysI with increasing NE levels in the diet. In phase II, increasing dietary NE levels also increased (P &lt; 0.05) FBW, ADG, NEI, LysI, and FC linearly. Overall, there was a linear increase (P &lt; 0.05) in ADG, NEI, LysI, and FC with increasing NE levels in the diet. The other performance variables were not affected (P &gt; 0.05) by the NE levels. There was an increase (P &lt; 0.05) in BF2 with increasing NE levels, but the other carcass characteristics were not altered (P &gt; 0.05). We recommended 2.60 Mcal of NE kg-1 in the diet for growing barrows from 30 to 70 kg.

Effect of dietary energy level in finishing phase on performance, carcass and meat quality in immunocastrates and barrows in comparison with gilts and entire male pigs

Immunocastration, a technique consisting of two vaccinations against gonadotropin-releasing hormone (GnRH), can be used as alternative to surgical castration of piglets. It reduces boar taint and allows higher economic and ecological efficiency compared to barrows. The feeding strategy of immunocastrates, however, can still be improved. After second vaccination, when immunisation becomes fully effective, feed intake of immunocastrates increases sharply. This study aimed to investigate whether energy intake of immunocastrates after second vaccination could be reduced by lowering the dietary energy level of the finishing phase, without negatively affecting animal performance and quality of pork production. We hypothesised that immunocastrates already reach their limits in voluntary feed intake after second vaccination, and therefore would not be able to compensate the lower dietary energy level, in contrast to barrows. Therefore, this study aimed to assess the effect of high-energy diet (HE, net energy (NE) = 10.2 MJ/kg) compared to low-energy diet (LE, NE = 8.8 MJ/kg) in barrows and immunocastrates and as a reference, gilts and entire male pigs on a standard high-energy diet were included. CP and standardised ileal digestible amino acid levels were similar in both diets. For each treatment, eight pen replicates of six pigs per pen were evaluated on performance, carcass quality, meat and fat quality, digestibility, economic and ecological sustainability, behaviour and effectiveness of immune response. No difference in feed intake of immunocastrates between LE and HE could be demonstrated. As a result, daily energy intake of immunocastrates was higher on HE compared to LE, which resulted in a higher daily gain on HE. Feed conversion ratio (FCR) of immunocastrates on HE did not differ significantly with FCR of entire males. Barrows did not show higher average daily gain on HE compared to LE. Nitrogen efficiency was better in HE compared to LE, without negative effects on digestibility, carcass quality, economic parameters, behaviour or immune response. Small positive effects on the palatability of the meat of immunocastrates on HE were observed, although consumers did not prefer one of both feeds. Immunocastration was successful in reducing sexual and aggressive behaviour as well as in lowering the prevalence of boar taint from 15% in EM to 0% in immunocastrates. However, in two out of 96 immunocastrates (one on HE and one on LE), the immunocastration was not fully effective. In conclusion, this study did not show advantages of feeding immunocastrates or barrows a low-energy diet.

Effect of stage of lactation and dietary starch content on endocrine-metabolic status, blood amino acid concentrations, milk yield, and composition in Holstein dairy cows

Milk yield and composition are modified by level and chemical characteristics of dietary energy and protein. Those factors determine nutrient availability from a given diet, and once absorbed, they interact with the endocrine system and together determine availability of metabolites to the mammary gland. Four multiparous dairy cows in early lactation and subsequently in late lactation were fed 2 diets for 28 d in a changeover design that provided, within the same stage of lactation, similar amounts of rumen fermentable feed with either high (HS) or low starch (LS). All diets had similar dietary crude protein (15.5% dry matter) and rumen-undegradable protein (∼40% of crude protein) content. Profiles of AA were calculated to be similar to that of casein. On d 28, [1-13C] Leu was infused into one jugular vein with blood samples taken at 0, 2, 4, 6, and 8 h, and cows milked at 0, 2, 4, 5, 6, 7, and 8 h from start of infusion. Isotopic enrichments of plasma Leu, keto-isocaproic acid, and milk casein were determined for calculation of Leu kinetics. Data were subjected to ANOVA using the MIXED procedure of SAS (SAS Institute Inc.), with time as repeated factor and cow as the random effect. Dry matter intake within each stage of lactation was similar between groups. Feeding LS resulted in lower blood glucose and greater ratio of bovine somatotropin to insulin. This response was associated with greater blood concentrations of nonesterified fatty acids and β-hydroxybutyrate, which might have contributed to greater milk fat content in LS-fed cows. Except for His, average concentrations of all AA in blood were higher in late than early lactation. Diet did not alter average plasma concentrations of AA. However, for most of the essential AA (particularly branched-chain), the HS diet led to a marked decrease in concentrations after the forage meal, resulting in significant differences between dietary groups in early lactation. In early-lactating cows fed HS, a greater reduction in plasma concentrations at 8 h relative to pre-feeding values (time zero) was observed for Met, Lys, and His, resulting in decreases of 27.9%, 33.6%, and 38.5%, respectively. A higher bovine somatotropin/insulin ratio in early lactation and in cows fed LS could possibly have led to greater breakdown and, consequently, higher AA flux from peripheral tissues. In LS-fed cows, higher mobilization of body fat and protein was confirmed by the greater body weight loss in both stages of lactation. Higher irreversible loss of [1-13C] Leu in early lactation suggested lower protein retention in peripheral tissues during early compared with late lactation. Milk yield, protein output, and composition were similar between groups at both stages of lactation, whereas milk coagulation was faster (lower curd firming rate) and with higher curd firmness in response to feeding HS in late lactation. Overall, data indicated that rate of carbohydrate fermentability in the rumen can modify the availability of metabolites to the mammary gland and consequently modify milk protein coagulation.

Effect of energy and protein levels in supplemental diets on performance of Rayeni cashmere does and goat kids under natural grazing conditions

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The Impact of Genotype and Age on Energy and Protein Utilization in Individually Housed Brown Laying Hens.

Simple SummaryAn investigation into whether the nutrient requirement of egg-laying hens has changed with genotype improvements was conducted. This study compared the response of individually housed laying hens of two different genotypes and ages. The strains used were a heritage breed in mid-lay and a modern breed at peak production. Energy was utilized with the same efficiency by both strains. All hens were able to adjust their feed intake to ensure that their energy requirements were met. The modern strain utilized protein slightly more efficiently than the heritage strain. It is unlikely that the nutrient requirements of modern layer strains have increased. More likely, requirements have decreased because modern hens are lighter and have a lower daily egg output (lay smaller eggs) despite their higher lifetime egg output. Regardless, feeding programs need to be adjusted for economic reasons and depend on achievable feed intakes under particular circumstances.Responses to dietary energy and protein levels were compared between two egg-laying genotypes. Individually housed hens of a historic strain (HS) and a modern strain (MS) were compared. In Experiment 1 (Exp.1), four levels of true metabolizable energy, corrected for zero nitrogen retention (TMEn) and four levels of total lysine, were offered from 30 to 40 weeks of age. In Experiment 2 (Exp.2), three levels of apparent metabolizable energy, corrected for zero nitrogen retention (AMEn) and four levels of standardized ileal digestible lysine (SID Lys), were fed from 20 to 30 weeks of age. A randomized factorial block design (4 × 4 Exp.1 and 3 × 4 Exp.2) was applied. Energy utilization for egg output (EO) did not differ (NS), and both strains maintained a constant kJ intake (NS). The efficiency of SID Lys utilization for EO differed, with the MS being the more efficient (p < 0.034). A single model could be used to predict feed intake, using BW, EO, AMEn and SID Lys (r = 0.716). In conclusion, it is unlikely that the requirements of modern layer strains have increased. However, feeding programs should be adjusted for economic reasons and are dependent upon achievable feed intake under particular circumstances.

Drivers of the increasing water footprint in Africa: The food consumption perspective

In Africa, water resources pervade multiple sustainable development goals (SDGs), which mainly focus on eliminating poverty (SDG 1) and hunger (SDG 2), promoting good health and well-being (SDG 3) and supporting clean water and sanitation (SDG 6). Africa's water scarcity problems have been worsened by population growth and climate change. Agriculture is the largest consumer of water in Africa, and a clear understanding of the water-food nexus is necessary to effectively alleviate water-related pressures on food security. Water footprint (WF) accounts and decompositions provide insights into water management planning for policy-makers. We investigated the WF of food consumption from 2000 to 2018 in 23 African countries and used the logarithmic mean Divisia index (LMDI) to decompose its driving forces into consumption structure, per capita food consumption, water intensity and population effect. The WF of food consumption increased from 609.8 km3 in 2000 to 1212.9 km3 in 2018, with an average annual growth rate of 3.7%. The population effect contributed most to this change (64.6%), followed by per capita food consumption (28.3%) and consumption structure (7.1%). Cereals (46.7%) and livestock (24.4%) were the major contributors to the increase in the total WF. Our findings highlight that controlling population growth and improving water efficiency are effective measures to relieve water-related pressures on food consumption. However, a healthy dietary structure must also be promoted because Africa's current dietary energy level is below the global average. Moreover, nine countries in the research area have an inadequate supply of dietary energy; this will inevitably drive the WF of food, as calories increase and diets change. This study is helpful for understanding the water-food nexus in Africa and provides strategies to conserve water and enhance food production.

Effects of Different Levels of Dietary Energy and Nutrient Density during the Pre-Peak and Peak Periods on Egg Quality in Hy-Line Brown Laying Hens

In this study, we investigated the effects of feeding diets with different levels of energy and nutrient density on the egg quality of laying hens during the pre-peak and peak periods. A total of 192 (Hy-line brown) laying hens were used in a 15-week trial. The hens were randomly allotted to one of four treatments, each with four replicates (12 hens per replication). We assessed the effects of four level of dietary energy (2,710, 2,850, 2,870 and 2,890 kcal/kg) and three levels of nutrient density (Methionine + Cysteine: 0.56%, 0.85%, 0.80% and Crude Protein: 14.5%, 19%, 18%). Differences in the energy and nutrient density contents of diets showed no significant effect (<i>P</i>&gt;0.05) on the average daily gain, average daily feed intake, feed conversion ratio, egg weight, or egg production of hens during the pre-peak and peak periods. However, hens subjected to 2,890 kcal/kg during the pre-peak period were found to lay eggs with significantly thicker shells, and yolk color was found to be significant enhanced in hens fed this diet during the pre-and peak periods. In contrast, we detected no significant effects of dietary energy or nutrient density on the Haugh unit or eggshell strength. In summary, increasing the energy level of diets from 2,710 to 2,890 kcal/kg was found to have positive effects on the shell thickness and yolk color of eggs produced by laying hens.

Combined effects of elevated rearing temperature and dietary energy level on heart morphology and growth performance of Tasmanian Atlantic salmon (Salmo salar L.).

Cardiac abnormalities may pose a threat to salmonid aquaculture due to their potential detrimental effect on fish health and welfare. The teleost heart is an extremely plastic organ with important morphological differences between wild and farmed fish that include ventricular shape, alignment of the bulbus arteriosus and epicardial fat deposition. However, little is known about how different factors and interactions among them may affect cardiac morphology of Atlantic salmon. To determine whether rearing temperature could induce cardiac malformations in large Tasmanian Atlantic salmon, we examined a range of cardiac morphology indicators and growth parameters in a population of 1-2kg seawater salmon (n=60 temperature-1 diet-1 ) exposed to control and elevated temperatures of 15 and 19°C, respectively, while fed one of two commercial feeds with different dietary energy levels. Most fish possessed conspicuous fat around the heart with a tendency towards a rounded ventricle and a more obtuse angle of the bulbus arteriosus. However, fish showed no significant differences in heart shape and bulbus alignment in relation to water temperature and dietary energy. These results suggest that cardiac morphology of large Atlantic salmon is unlikely to be affected by rearing temperature and dietary energy during the grow-out phase.