Increased Weaning Weight Research Articles

Effects of Dietary Taurine Supplementation to Gilts during Late Gestation and Lactation on Offspring Growth and Oxidative Stress.

Simple SummaryPrevious studies showed that gilts had elevated oxidative stress during late gestation and lactation, and could affect offspring growth. Taurine (Tau) is an important regulator of oxidative stress and possesses growth-enhancing properties. Our results suggested that taurine supplementation during late gestation and lactation of gilts increased growth performance in piglets through improved milk quality of gilts and intestinal morphology and barrier function of offspring.Birth is one of the most important events of animal production agriculture, as newborns are abruptly forced to adapt to environmental and nutritional disruptions that can lead to oxidative damage and delay in growth. Taurine (Tau) is an important regulator of oxidative stress and possesses growth-enhancing properties. In the present study, we investigated the effects of dietary Tau supplementation in gilts during late gestation and lactation on the growth performance of piglets by assessing intestinal morphology and barrier function, and oxidative stress status. Sixteen gilts were randomly allocated to the Con (basal diet) and Tau (basal diet with 1% Tau) groups from 75 d of gestation to weaning. Maternal dietary Tau supplementation significantly increased weaning weight and average daily gain weight in piglets. Piglets in the Tau group had higher villus height and villus height-to-crypt depth ratio (VCR), ZO-1 protein expression, and secretory immunoglobulin A (sIgA) content in the jejunum. Meanwhile, Tau bebeficial affected the milk quality of gilts, as indicated by decreased malondialdehyde (MDA) concentration and increased total superoxide dismutase (T-SOD), total antioxidative capability (T-AOC), glutathione peroxidase (GPx), and catalase (CAT) activity. Furthermore, Tau supplementation increased T-SOD activity in plasma and SOD2 protein expression in the jejunum in the piglets. In conclusion, this study provides evidence that dietary Tau supplementation to gilts improves growth performance in piglets, owing to improved intestinal morphology and barrier function, as well as inhibition of oxidative stress.

Oral administration of Lactobacillus rhamnosus GG to newborn piglets augments gut barrier function in pre-weaning piglets.

To understand the effects of Lactobacillus rhamnosus GG (ATCC 53103) on intestinal barrier function in pre-weaning piglets under normal conditions, twenty-four newborn littermate piglets were randomly divided into two groups. Piglets in the control group were orally administered with 2 mL 0.1 g/mL sterilized skim milk while the treatment group was administered the same volume of sterilized skim milk with the addition of viable L. rhamnosus at the 1st, 3rd, and 5th days after birth. The feeding trial was conducted for 25 d. Results showed that piglets in the L. rhamnosus group exhibited increased weaning weight and average daily weight gain, whereas diarrhea incidence was decreased. The bacterial abundance and composition of cecal contents, especially Firmicutes, Bacteroidetes, and Fusobacteria, were altered by probiotic treatment. In addition, L. rhamnosus increased the jejunal permeability and promoted the immunologic barrier through regulating antimicrobial peptides, cytokines, and chemokines via Toll-like receptors. Our findings indicate that oral administration of L. rhamnosus GG to newborn piglets is beneficial for intestinal health of pre-weaning piglets by improving the biological, physical, and immunologic barriers of intestinal mucosa.

PSX-8 Use of anabolic implants in calves to increase weaning weight and backgrounding gains.

PSX-8 Use of anabolic implants in calves to increase weaning weight and backgrounding gains.

Vitamin A administration at birth promotes calf growth and intramuscular fat development in Angus beef cattle

BackgroundMarbling, or intramuscular fat, is an important factor contributing to the palatability of beef. Vitamin A, through its active metabolite, retinoic acid, promotes the formation of new fat cells (adipogenesis). As intramuscular adipogenesis is active during the neonatal stage, we hypothesized that vitamin A administration during the neonatal stage would enhance intramuscular adipogenesis and marbling.MethodsAngus steer calves (n = 30), in a completely randomized design, were randomly allotted to three treatment groups at birth, receiving 0, 150,000, or 300,000 IU of vitamin A at both birth and one month of age. A biopsy of the biceps femoris muscle was collected at two months of age. After weaning at 210 d of age, steers were fed a backgrounding diet in a feedlot until 308 d of age, when they were transitioned to a high concentrate finishing diet and implanted with trenbolone/estradiol/tylosin mixture. Steers were harvested at an average of 438 d of age. All diets were formulated to meet nutrient requirements.ResultsWeaning weight and weight during the backgrounding phase were linearly increased (P < 0.05) by vitamin A level, though no difference in body weight was observed at harvest. Intramuscular fat of steers at 308 d of age, measured by ultrasound, quadratically increased (P < 0.05) with vitamin A level from 4.0±0.26 % to 4.9±0.26 %. Similarly, carcass marbling score in the ribeye quadratically increased (P < 0.05).ConclusionAdministration of vitamin A at birth increased weaning weight and enhanced marbling fat development. Thus, vitamin A administration provides a practical method for increasing marbling and early growth of beef cattle.

Forage management and concentrate supplementation effects on performance of beef calves

Proper grazing management is the most effective practice to provide adequate forage quantity and quality to cow–calf systems, and optimise beef-calf performance in tropical and subtropical regions. Supplementation of beef calves is not a commonly used management practice in beef-cattle production, primarily because calves can benefit from the cow’s milk production to offset some limitations in forage quantity and quality. Creep-feeding and supplementation of early weaned calves are the two main strategies to supplement beef calves. Creep-feeding can be used to overcome limited herbage allowance, improve calves uniformity, supply extra nutrients for calves, provide adaptation to concentrate diets before weaning, and increase weaning weight. Early weaning is an effective management practice to increase the likelihood of re-breeding of first-calf beef heifers in the south-eastern USA; however, it was observed that concentrate supplementation is necessary for early weaned calves to achieve desirable levels of gain on pasture in tropical and subtropical regions. In addition, concentrate supplementation during early stages of a calf life may permanently change calf development and performance in a process called ‘metabolic imprinting’. The metabolic imprinting concept in production agriculture is in the early stages of knowledge and further research should elucidate the benefits of this management practice in beef-cattle production.

Animal models of maternal high fat diet exposure and effects on metabolism in offspring: a meta‐regression analysis

SummaryAnimal models of maternal high fat diet (HFD) demonstrate perturbed offspring metabolism although the effects differ markedly between models. We assessed studies investigating metabolic parameters in the offspring of HFD fed mothers to identify factors explaining these inter‐study differences. A total of 171 papers were identified, which provided data from 6047 offspring. Data were extracted regarding body weight, adiposity, glucose homeostasis and lipidaemia. Information regarding the macronutrient content of diet, species, time point of exposure and gestational weight gain were collected and utilized in meta‐regression models to explore predictive factors. Publication bias was assessed using Egger's regression test.Maternal HFD exposure did not affect offspring birthweight but increased weaning weight, final bodyweight, adiposity, triglyceridaemia, cholesterolaemia and insulinaemia in both female and male offspring. Hyperglycaemia was found in female offspring only. Meta‐regression analysis identified lactational HFD exposure as a key moderator. The fat content of the diet did not correlate with any outcomes. There was evidence of significant publication bias for all outcomes except birthweight.Maternal HFD exposure was associated with perturbed metabolism in offspring but between studies was not accounted for by dietary constituents, species, strain or maternal gestational weight gain. Specific weaknesses in experimental design predispose many of the results to bias.

Sire line of pigs affects weaning weight, growth performance, and carcass characteristics of offspring.

Today, early weaning is more frequently applied by the modern pig breeder to obtain more litters per year. In addition, more and more European pig breeders apply a batch management system, which allows weaning to occur at fixed time points but entails that the offspring are treated at the litter level and not as individuals. Both evolutions might result in weaning lightweight piglets, which can cause, e.g., growth retardation of the offspring. Hence, the objective of this research was to improve the weaning weight of piglets of the same age by breeding with a highly conformed sire line. Therefore, a total of 23 sows were inseminated, 10 sows with semen of a well-conformed sire line (sire line B) and 13 sows with semen of a less conformed boar (sire line A). In total, 299 offspring were observed to monitor behavior, growth performance, and carcass characteristics. Subsequently, linear mixed models were developed to analyze the growth performance and carcass characteristics wherein only variables classified as significant ( < 0.05) were introduced as fixed factors. Results indicate that no significantly increased weaning weight could be accomplished by breeding with semen of sire line B. This could be due to the significant ( < 0.05) shorter gestation length of sows inseminated with semen of sire line B. However, the offspring of sire line B was defined by better carcass classification characteristics. Furthermore, this study presents that the mean birth weight of each piglet was significantly lower if a bigger litter size was recorded. When considering behavior, it was observed that piglets that did not seclude themselves from the litter had a significantly greater daily weight gain from birth to weaning compared to piglets that showed signs of isolation from the litter. A significantly greater daily gain from birth to slaughter was established for piglets with a greater birth weight. Also, results indicate that barrows had a significantly greater daily growth from weaning to slaughter than gilts. To conclude, this research determines that breeding with highly conformed sire lines does not improve the weaning weight of the offspring and thus cannot serve as a solution for early weaning. However, more research is required by performing more experiments with a greater number of boars and sows to confirm this result. In general, this study allows researchers to continue to improve and standardize the weaning weight of piglets of the same age.

Effects of dietary enrichment with a marine oil-based n-3 LCPUFA supplement in sows with predicted birth weight phenotypes on birth litter quality and growth performance to weaning

The effects of a marine oil-based n-3 long-chain polyunsaturated fatty acid (mLCPUFA) supplement fed to the sow from weaning, through the rebreeding period, during gestation and until end of lactation on litter characteristics from birth until weaning were studied in sows with known litter birth weight phenotypes. It was hypothesized that low birth weight (LBW) litters would benefit more from mLCPUFA supplementation than high birth weight litters. A total of 163 sows (mean parity=4.9±0.9) were rebred after weaning. Sows were pair-matched by parity and litter average birth weight of the previous three litters. Within pairs, sows were allocated to be fed either standard corn/soyabean meal-based gestation and lactation diets (CON), or the same diets enriched with 0.5% of the mLCPUFA supplement at the expense of corn. Each litter between 9 and 16 total pigs born was classified as LBW or medium/high average birth weight (MHBW) litter and there was a significant correlation (P<0.001) between litter average birth weight of the current and previous litters within sows (r=0.49). Sow serum was harvested at day 113 of gestation for determination of immunoglobulin G (IgG) concentrations. The number of pigs born total and alive were lower (P=0.01) in mLCPUFA than CON sows, whereas the number of stillborn and mummified pigs were similar between treatments. Number of stillborns (trend) and mummies (P<0.01) were higher in LBW than MHBW litters. Tissue weights and brain : tissue weight ratios were similar between treatments, but LBW litters had decreased tissue weights and increased brain : tissue weight ratios compared with MHBW litters. Placental weight was lower (P=0.01) in LBW than MHBW litters, but was not different between treatments. Average and total litter weight at day 1 was similar between treatments. mLCPUFA increased weaning weight (P=0.08) and average daily gain (P<0.05) in MHBW litters, but not in LBW litters. Pre-weaning mortality was similar between treatments, but was higher (P<0.01) in LBW than MHBW litters. IgG concentration in sow serum was similar between treatments and litter birth weight categories. In conclusion, litter birth weight phenotype was repeatable within sows and LBW litters showed the benchmarks of intra-uterine growth retardation (lower placental weight and brain sparing effects). As maternal mLCPUFA supplementation decreased litter size overall, only improved litter growth rate until weaning in MHBW litters, and did not affect pre-weaning mortality, maternal mLCPUFA supplementation was not an effective strategy in our study for mitigating negative effects of a LBW litter phenotype.

Efeitos do fornecimento de dietas pré-desmame para leitões: uma revisão

O fornecimento de alimento complementar ao leite da porca durante a lactação (creep feed) é um manejo comumente recomendado para produtores. A prática foi introduzida como estratégia para minimizar os efeitos deletérios do desmame abrupto e precoce, bem como para uniformizar as leitegadas a serem desmamadas, aumentar o peso ao desmame e acelerar a adaptação do trato gastrintestinal dos leitões a dietas sólidas. As dietas creep feed são formuladas buscando-se altos níveis de digestibilidade e palatabilidade e incluem ingredientes de alta qualidade e alto custo. No entanto, resultados de pesquisas que indiquem que a simples oferta de creep feed é eficiente para minimizar os efeitos deletérios do desmame ou para facilitar a adaptação dos leitões a dietas iniciais ainda são escassos e pouco consolidados. O objetivo desse trabalho foi revisar os fatores que influenciam o consumo de creep feed, os efeitos do consumo dessas dietas sobre o desempenho durante a lactação, bem como as possíveis influências sobre o desenvolvimento enzimático, a ocorrência de diarreias e o desempenho pós-desmame de leitões desmamados entre 21 e 28 dias de idade. Os resultados encontrados indicam que leitões lactentes não apresentam maturidade intestinal suficiente para que estas dietas sejam voluntariamente consumidas e adequadamente digeridas. Mesmo os animais dispostos ao consumo não o fazem em quantidade suficiente para promover a adaptação enzimática ou melhorar o desempenho pós-desmame. Ao contrário do esperado, o consumo de creep feed, especialmente se em baixas quantidades, pode estar associado a sensibilização do trato gastrintestinal, que resulta em reações de hipersensibilidade e diarreia pós-desmame. Concluiu-se que a simples oferta de creep feed não é eficiente para promoção do crescimento na lactação e no pós-desmame, ou para facilitar a adaptação de leitões desmamados precocemente a dietas sólidas. Portanto, destaca-se a necessidade de pesquisas na área, visando o desenvolvimento de técnicas que possam, efetivamente, minimizar as perdas decorrentes da prática de desmamar leitões precocemente.

Selection for feed efficiency traits and correlated genetic responses in feed intake and weight gain of Nellore cattle1

The objectives of this study were to estimate genetic parameters for indicator traits of feed efficiency and to recommend traits that would result in better responses to selection for increased weaning weight (weaning weight adjusted to 210 d of age [W210]), ADG, and metabolic BW (BW(0.75)) and lower DMI. Records of W210 from 8,004 Nellore animals born between 1978 and 2011 and postweaning performance test records from 678 males and females born between 2004 and 2011 were used. The following feed efficiency traits were evaluated: G:F, partial efficiency of growth (PEG), relative growth rate (RGR), Kleiber's ratio (KR), residual feed intake (RFI), residual weight gain (RWG), and residual intake and gain (RIG). Covariance and variance components were estimated by the restricted maximum likelihood method using multitrait analysis under an animal model. Estimates of genetic gain and correlated responses were obtained considering single-stage and 2-stage selection. Heritability estimates were 0.22 ± 0.03 (W210), 0.60 ± 0.08 (DMI), 0.42 ± 0.08 (ADG), 0.56 ± 0.06 (BW(0.75)), 0.19 ± 0.07 (G:F), 0.25 ± 0.09 (PEG), 0.19 ± 0.07 (RGR), 0.22 ± 0.07 (KR), 0.33 ± 0.10 (RFI), 0.13 ± 0.07 (RWG), and 0.19 ± 0.08 (RIG). The genetic correlations of DMI with W210 (0.64 ± 0.10), ADG (0.87 ± 0.06), and BW(0.75) (0.84 ± 0.05) were high. The only efficiency traits showing favorable responses to selection for lower DMI were G:F, PEG, RFI, and RIG. However, the use of G:F, PEG, or RFI as a selection criterion results in unfavorable correlated responses in some growth traits. The linear combination of RFI and RWG through RIG is the best selection criterion to obtain favorable responses in postweaning growth and feed intake of Nellore cattle in single-stage selection. Genetic gains in feed efficiency are expected even after preselection for W210 and subsequent feed efficiency testing of the preselected animals.

Effects of different levels of protein with or without probiotics on growth performance and blood metabolite responses during pre- and post-weaning phases in male Kurdi lambs

The effects of different levels of protein and probiotics offered before and after weaning on growth performance, blood metabolites, and rumen fermentation were investigated in two experiments. In Exp. 1 (the pre-weaning phase), twenty-four single lambs, 10 days of age with an average live body weight of 15.3±1.8kg, were individually penned and randomly assigned to the treatments in a 2×2 factorial arrangement of protein levels (16% vs. 18% CP of DM) and probiotic levels (0 vs. 2g Protexin®/d). The diets consisted of 20% lucerne hay and 80% concentrate (on a DM basis) offered over a total of 60days including 15days of adjustment period and 45days of experimental period until weaning. The lambs were transferred to separate pens where they were allowed to suckle their respective dams twice a day (in the morning and in the evening). The experimental procedure in Exp. 2 (the post-weaning phase) was the same as that in Exp. 1 except for the protein levels (14.5% vs. 16.5% CP of DM) administered and the lucerne hay (30.0%) included in the diets. Twenty-four 78-days-old lambs, weighing 30.5±2.6kg, were individually penned and offered the diets for 60 days inclusive of 15 days of feed adjustment. The results of Exp. 1 showed that raising the protein content of the diet from 16% to 18% CP led to increased weaning weights (28.2 vs. 32.4±1.83kg; P<0.05), average daily gain (ADG) (288g/d vs. 381±19.4g/d; NS), and feed intake (490g/d vs. 541±19.4g/d; P<0.05). However, no significant differences were observed in food conversion ratio (FCR; P>0.05) among the treatments. BUN concentration was on the 18% CP diet (14.3mg/dl vs. 17.4±0.50mg/dl; P<0.05), and on diets without probiotics compared to those with probiotics (15.0mg/dl vs. 16.7±0.50mg/dl; P<0.05). Probiotic supplementation increased feed intake (485g/d vs. 546±19.4g/d; P<0.05) and rumen NH3-N (7.13mg/dl vs. 8.39±0.19mg/dl; P<0.05) during the pre-weaning period. Cortisol concentration was significantly lower (P<0.05) in lambs fed the probiotic significantly lower in the 16% CP diet than that supplemented diets than in those fed probiotic-lacking diets 24h after weaning (17.3mg/dl vs. 16.6±0.21mg/dl) and 48h after weaning (16.8mg/dl vs. 15.9±0.21mg/dl). In Exp. 2, final weight, ADG, feed intake, and FCR were not significantly different among the diets with different protein levels or between those with or without probiotic supplementation. In addition, feeding diets with the lower CP level (14.5% vs. 16.5%; DM basis) resulted in lower concentrations of blood metabolites, urea nitrogen (19.9mg/dl vs. 25.0±1.16mg/dl; P<0.05), rumen pH (5.99±vs. 6.22±0.03; P<0.05), and ruminal NH3-N (10.99mg/dl vs. 11.22±0.03mg/dl; P<0.05). It was concluded that the higher protein level (18% CP; DM basis) fed during the pre-weaning phase led to increasing feed intake and weaning weight compared to the lower CP diet (16%) but that a higher level of protein in the post-weaning diet (16.5% vs. 14.5% CP; DM basis) did not affect performance. Supplementing the diets with probiotics might have reduced stress (lower cortisol concentration) after weaning but it did not improve the performance of the lambs.

Bayesian analysis of selection for greater weaning weight while maintaining birth weight in beef cattle

An experimental Hereford herd established in 1960 was used from 1986 to 2006 to select for increased weaning weight (W) without increasing birth weight (B). Data were B and W collected over the 47 yr from 2,124 calves. Including ancestors, the pedigree file had 2,369 animals. Selection was practiced only in males. In the first stage (1986 to 1993), mass-selected bulls were chosen with the index I = B + 9374.76 RDG (relative daily gain). From 1994 to 2006, the selection criterion for bull i was I(i) = BLUP(i)(WD) - 2.33 BLUP(i)(BD), where the BLUP were for the direct BV of B (BD) and W (WD), respectively. Predictions were obtained from a 2-trait animal model with B having only BD, and W with WD and WM (maternal additive effects). Selection response was estimated using a Bayesian approach by means of the Gibbs sampler for a 2-trait animal model including BD, BM (maternal BV for B), WD, and WM. Estimated heritabilities for BD, BM, WD, and WM were 0.40, 0.23, 0.05, and 0.23, respectively. The correlation between BD and BM was close to zero (0.01), and between WD and WM was positive (0.37). The correlation between BD and WD was 0.07, and between BM and WM was 0.58. The 2 methods used to estimate selection response gave similar results. In both periods BD decreased, whereas BM increased. The reduction of BD due to selection was slightly larger in the second period than in the first one. The regression of BV for W increased due to selection in both stages, but selection response was 21.6% larger from 1986 to 1992 than from 1993 to 2006. The maternal effect, WM increased more than 3 times compared with WD in the first period, but ended up being almost the same value as WD in period 2. The Bulmer effect was manifested by the decrease in magnitude of all (co)variance components during selection. It is concluded that selection to increase BW at weaning in beef cattle, although not increasing BW at birth, was moderately effective.

Relationship of Lactate Dehydrogenase Activity with Body Measurements of Beef Cows and Calves

Angus × Charolais cows (n = 87) and calves (n = 86) were utilized to examine relationships among lactate dehydrogenase (LDH) activity and age, sire breed, and body measurements of beef cows, and the relationship between maternal LDH activity in late gestation and subsequent calf birth weight (BRW), hip height at weaning (CALFHH), and adjusted weaning weight (205WW). At 62 d prepartum, cow BW, BCS, and hip height (COWHH) were recorded, and cow LM area (LMA), intramuscular fat percentage, and rib fat were measured via ultrasonography. Serum was collected from each cow and forward LDH (LDHf) and reverse LDH (LDHr) activities were determined. Correlation coefficients showed an inverse relationship between cow LDHr activity with CALFHH (r = −0.28; P = 0.01) and 205WW (r = −0.21; P = 0.05) of calves. First canonical correlation of cow LDHr and LDHf activities, BW and COWHH with 205WW and CALFHH was significant (r = 0.57; P = 0.001). The cow traits including LMA, rib fat, and intramuscular fat percentage were correlated (r = 0.36; P = 0.02) with 205WW and CALFHH. A combination of cow LMA, LDHr activity, BW, and COWHH was correlated (r = 0.58; P < 0.001) to a combination of 205WW and CALFHH. Decreased LDHr activity in prepartum cows was associated with taller and heavier calves at weaning. Ultrasonography of LMA, and LDHr activity along with BW and COWHH of cows during the last trimester of pregnancy could be useful in identifying calves with subsequent increased weaning weight.

Effects of Dietary Lysine Supplementation on the Performance of Lactating Sows and Litter Piglets during Different Seasons

The effect of dietary lysine supplementation on the performance of crossbred lactating sows (n = 49, total 92 litters) and suckling piglets during the warm and cool seasons was studied. Sows were randomly allocated to one of two experimental diets, which were fed throughout a 28-day lactation period. Two diets were formulated based on corn-soybean meal with 6% wheat bran, containing 15% crude protein, and with or without 0.25% lysine-HCl supplementation. No interaction was observed between season and dietary lysine supplementation. Dietary lysine supplementation significantly (p<0.05) increased weaning weight (7.11 vs. 6.46 kg) and daily gain (0.20 vs. 0.18 kg) of piglets. During the warm season lactating sows had significantly lower feed intake (3.78 vs. 6.11 kg, p<0.01), higher weight loss (19.81 vs. 9.73 kg, p<0.01) and backfat loss (0.23 vs. 0.06 cm, p<0.01), longer interval from weaning to estrus (9.32 vs. 6.21 days, p<0.05), lower litter weight gain (42.13 vs. 52.90 kg, p<0.01) and lower daily gain (0.17 vs. 0.21 kg, p<0.01) than lactating sows during the cool season. The results indicate that the influences of dietary treatment and season were independent. The 15.0% CP lactation diet with 0.25% lysine-HCl supplementation did not improve the performance of lactating sows and litter piglets, which was impaired by the warm season. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 4 : 568-572)

Evidence of a major gene influencing hair length and heat tolerance in Bos taurus cattle.

Evidence was found that supports the existence of a major gene (designated as the slick hair gene), dominant in mode of inheritance, that is responsible for producing a very short, sleek hair coat. Cattle with slick hair were observed to maintain lower rectal temperatures (RT). The gene is found in Senepol cattle and criollo (Spanish origin) breeds in Central and South America. This gene is also found in a Venezuelan composite breed, the Carora, formed from the Brown Swiss and a Venezuelan criollo breed. Two sets of backcross matings of normal-haired sire breeds to Senepol crossbred dams assumed to be heterozygous for the slick hair gene resulted in ratios of slick to normal-haired progeny that did not significantly differ from 1:1. Data from Carora x Holstein crossbred cows in Venezuela also support the concept of a major gene that is responsible for the slick hair coat of the Carora breed. Cows that were 75% Holstein: 25% Carora in breed composition segregated with a ratio that did not differ from 1:1, as would be expected from a backcross matinginvolving a dominant gene. The effect of the slick hair gene on RT depended on the degree of heat stress and appeared to be affected by age and/or lactation status. The decreased RT observed for slick-haired crossbred calves compared to normal-haired contemporaries ranged from 0.18 to 0.4 degrees C. An even larger decrease in RT (0.61 degrees C; P < 0.01) was observed in lactating Carora x Holstein F1 crossbred cows, even though it did not appear that these cows were under severe heat stress. The improved thermotolerance of crossbred calves due to their slick hair coats did not result in increased weaning weights, possibly because both the slick and normal-haired calves were being nursed by slick-haired dams. There were indications that the slick-haired calves grew faster immediately following weaning and that their growth during the cooler months of the year was not compromised significantly by their reduced quantity of hair. In the Carora x Holstein crossbred cows there was a positive effect of slick hair on milk yield under dry, tropical conditions.

Effect of pre- and post-weaning management on subsequent pig performance to slaughter and carcass quality

AbstractThe aim of this study was to assess the effect of weaning weight and post-weaning diet on the performance of weaned pigs. In experiment 1, 30 litters with more than 10 pigs born alive per litter were selected. At 11 days of age, pigs of average weight for the litter were removed from 15 litters so that eight pigs remained per sow. These litters were given access to creep food (16·5 MJ digestible energy (DE) per kg and 18·7 g/kg lysine). The remaining litters were left complete and were not given creep food. Pigs were weaned at 28 days of age and pairs of pigs (a male and a female littermate of similar weight) were formed from each litter (no. = 54 pairs). Pairs were blocked on the basis of litter origin and weight and assigned at random to one of the following treatments: (1) 10 kg starter diet (16·1 MJ DE per kg and 17·4 g/kg lysine) followed by link diet (15·3 MJ DE per kg and 15·0 g/kg lysine) to 27 days (high dietary regimen; HDR); or (2) 4 kg starter diet, 10 kg link diet and weaner diet to 27 days (low dietary regimen; LDR). Thereafter pigs were given common diets to slaughter at about 95·6 kg live weight. On experiment 2, four pigs (two light and two heavy) were taken from each of 32 litters (no. = 128 pigs; age = 22 days), blocked on sex, litter origin, and weaning weight and within weight category individually assigned at random to two dietary treatments: (1) high density diet (16·1 MJ DE per kg and 17·4 g/kg lysine); and (2) low density diet (15·1 MJ DE per kg and 15·7 g/kg lysine). The duration of the experiment was 26 days. In experiment 1, reducing litter size and creep feeding increased weaning weight by 0·6 kg (P 0·05). This weight advantage at weaning was lost by day 14 post weaning (P &gt; 0·05). From day 0 to day 27 post weaning daily gain was 472 and 427 g/day (s.e.12·8; P 0·05) and food conversion efficiency was 1·26 and 1·36 g/g (s.e. 0·026; P 0·05) for HDR and LDR, respectively. In experiment 2, weaning weight was 7·1 and 5·8 kg (s.e. 0·08; P 0·01) and pig weight at day 26 post weaning was 17·5 and 15·4 kg (s.e.0·23; P 0·01) for heavy and light weight categories, respectively. In the period from day 0 to 26, food intake was 440 and 396 g/day (s.e. 8·0; P 0·01) and daily gain was 389 and 355 g/day (s.e. 8·0; P &lt; i 0·01) for heavy and light weight categories, respectively. Weaning weight was found to be a good determinant of weight at day 26 when terms for litter origin were included (R2 = 0·67; P 0·001 for the high density diet and R2 = 0·77; P 0·001 for the low density diet). It is concluded that weaning weight can be increased by pre-weaning management but that this weight advantage is lost in the early post-weaning period. Where weaning weight was naturally higher the weight advantage was still evident at day 26 post weaning.

Production by ewes rearing single or twin lambs: effects of dietary crude protein percentage and supplemental zinc methionine1

Eighty Targhee ewes with single or twin lambs were used to investigate the effects of chelated zinc methionine and level of dietary CP on milk and wool production, DMI, and ewe and lamb BW change. Treatments were arranged as a 2 x 2 x 2 factorial. Dietary treatments started 30 d prepartum and continued until 42 d postpartum. Milk production was estimated at 4, 10, 18, and 28 d postpartum. During gestation, DMI by ewes receiving zinc methionine and the 14.9% CP diet was greater (P < .10) than DMI by ewes not supplemented with zinc methionine and ewes fed the 11.3% CP diet. Ewes fed the 14.9% CP diet tended (P < .14) to gain more BW from 30 d prepartum to 4 d postpartum and lose more BW from 4 to 42 d postpartum than ewes fed the 11.3% CP diet. Ewes fed zinc methionine and the 14.9% CP diet produced more (P < .10) milk on d 28 than their counterparts. Ewes rearing twins produced more (P < .05) milk on d 4, 10, and 18 than ewes rearing single lambs. However, milk production on d 28 was not affected by number of lambs reared (P = .68). Lamb ADG at 28, 42, and 59 d postpartum was greater (P < .05) for both the zinc methionine treatment and the 14.9% CP diet. Zinc methionine (P = .11) and the 14.9% CP diet (P = .02) increased weaning weights by 6 and 9%, respectively. We conclude that both the zinc methionine supplement and the 14.9% CP diet resulted in more persistent milk production. In addition, when ewes and lambs were fed for an average of 42 d during early lactation, a 14.9% CP diet, and to a lesser degree, a chelated zinc methionine supplement, lamb weaning weights were improved.

Biology and control of tabanids, stable flies and horn flies.

Tabanids are among the most free-living adult flies which play a role as livestock pests. A single blood meal is used as a source of energy for egg production (100-1,000 eggs per meal), and females of certain species can oviposit before a blood meal is obtained (autogeny). Therefore, the maintenance of annual populations requires successful oviposition by only 2% of females. Wild animal blood sources are usually available to maintain annual tabanid populations. Larval habitats are also independent of domestic livestock. Thus, the use of repellents or partial repellents is the only effective chemical strategy to reduce the incidence of tabanids on livestock. Permanent traps (and possibly treated silhouette traps) can be employed to intercept flies. Selective grazing or confinement can also reduce the impact of tabanids. Stable fly adults are dependent on vertebrate blood for survival and reproduction, but the amount of time spent in contact with the host is relatively small. Stable fly larvae develop in manure, spilled feed and decaying vegetation. Management of larval habitats by sanitation is the key to stable fly control. Treatment of animals with residual insecticides can aid in control; thorough application to the lower body parts of livestock is important. Proper use of modified traps, using either treated targets or solar-powered electrocution grids, can be effective in reducing stable fly populations. Adult horn flies spend the major part of their time on the host, and the larvae are confined to bovid manure. Therefore, almost any form of topical insecticide application for livestock is effective against horn flies, in the absence of insecticide resistance. Treatments should be applied when economic benefit is possible; economic gains are associated with increased weaning weights and weight gains of yearling and growing cattle. Oral chemical treatments (insect growth regulators or insecticides) administered at appropriate rates via bolus, water, food or mineral mixtures can inhibit horn fly larval development. However, adult horn fly movement among cattle herds limits the use of larval control for horn fly population management. The augmentation of native parasites, predators and competitors has been attempted and even promoted for horn fly and stable fly control, but evidence for the success of such programmes is equivocal.

The economic effect of estrus synchronization in beef heifers on average weaning weight of calves

Prostaglandin was used to induce estrus in 129 Hereford × Holstein heifers for artificial insemination. At the start of the breeding season heifers were observed twice daily and inseminated 12 hours after first being observed in estrus. On the morning of the sixth day of the breeding season all heifers not yet observed in estrus or inseminated were treated with prostaglandin (25 mg Lutalyse R). Observation was continued and heifers were bred 12 hours after first observed in estrus. Of the 129 heifers 33 were inseminated before prostaglandin treatment, the remainder of the heifers were bred within 4 days of treatment. Two heifers developed cysts and did not express estrus. First service pregnancy rates were 70% before treatment and 79% after treatment. All heifers were inseminated the first time within the first 10 days of the breeding season and 100 pregnancies occurred in the first 10 days of the season. As a result median days to pregnancy was 8. Calves were all weaned and weighed at approximately 150 days of age. These results were then used to model the economic impact of estrus synchronization of beef heifers on the increased weaning weights of their calves. Prostaglandin treatment altered the distribution of pregnancies and resulted in a cluster of conceptions from Day 7 to 10 of the breeding season with no conceptions from Day 11 to 19. In order to study the influence of estrus synchronization on weaning weights a simulation model was constructed. All heifers that conceived on the first service after prostaglandin were assigned an alternate date of conception from Day 7 to 21 of the breeding season with a random number generator. In this way a uniform random distribution of pregnancies over the first 21 days of the breeding season was constructed. An alternate calving date was then estimated using the known gestation length and this date was used to calculate the weaning weight of the calf using the known weight per day of age. The average weaning weight of the uniform random distribution was then compared to the synchronized distribution with Student's t -test. The simulation model was repeated 10 times and each time weaning weights of the uniform random distribution were significantly less than with the synchronization program (p<.01). At a value of $4.00 for prostaglandin and $1.76 for each kilogram of calf the average increase of 3.8 kgs in weaning weight per calf resulted in a return on investment of $1.92 for every dollar invested in prostaglandin.

Influence of level of supplemental alfalfa hay on the performance of beef cows grazing winter bluestem range (1992)

One hundred thirteen pregnant Hereford x Angus cows were used to study the effect of increasing levels of supplemental alfalfa hay on performance when grazing winter bluestem range. Although no differences were observed in reproductive performance, increasing the amount supplemental alfalfa from approximately .5% up to 1.0% of body weight resulted in increased weight gain and reduced condition loss in cows and increased weaning weight in calves. However, time spent grazing was significantly decreased in those groups receiving larger amounts of supplemental alfalfa.