The reduction in feed intake and growth rate that occurs following weaning is of major economic consequence to the pig industry. Currently, a range of antimicrobial products can be used to minimise the impact of weaning on piglet health and subsequent performance. However, the use of these products in pig diets is subject to increasing restriction worldwide because of perceived risks to public health and to the environment. Thus, alternative methods are required to mitigate the growth check that almost invariably occurs after weaning in most production systems. Piglets produced outdoors are claimed to experience less of a growth check at weaning and to be able to thrive in relatively unsophisticated weaner accommodation. However, these claims have not been substantiated under Western Australian conditions, nor a scientific basis for these claims established. Consequently, a series of experiments was designed to test the general hypothesis for this thesis – ‘the gut structure and function, and lifetime performance of the weaned pig are affected by its pre- and post-weaning rearing environments’. Experiment 1 was conducted in two parts to quantify differences in the growth performance, health and gut structure of weaner pigs produced indoors or outdoors and reared in conventional or deep-litter pens. The weaner diet in the first part of the experiment contained 100 ppm of olaquindox and 3,000 ppm of zinc oxide (Exp1a). This experiment was repeated without using dietary antimicrobial products (Exp1b). Experiment 2 was conducted in conventional buildings to examine the effect of exposing piglets in lactation to similar substrates to those available to outdoor piglets used in Exp1a and Exp1b in the absence of other differences in the outdoor production milieu. Pre-weaning environments in Exp1a (indoor production (IP) and outdoor production (OP)) appeared to have little effect on gut structure and overall growth rate but significantly affected carcass composition, whereas post-weaning environments (conventional (C) or deep-litter (DL)) affected both overall growth rate and carcass composition. Although feed disappearance was similar, OP pigs grew faster than IP pigs in the first 47 d after weaning in Exp1a but not in Exp1b. Lifetime growth rate (GR), P2 backfat, feed disappearance and feed conversion ratio (FCR) were not significantly affected by the production environment in Exp1a whereas OP pigs grew slower with higher P2 backfat and FCR in Exp1b. Interestingly, OP pigs had heavier carcass weights and higher dressing percentages than IP pigs in both parts of the experiment. The effects of post-weaning environment were more consistent as DL pigs grew faster, were fatter, and had higher carcass weights and dressing percentages than C pigs. Villus height and crypt depth of IP and OP pigs were not different at 21 (weaning) or 28 d, but villus height decreased and crypt depth increased in the week after weaning. Pigs reared in C pens had greater faecal concentrations of volatile fatty acids than pigs in DL, indicating that the latter ingested sufficient straw to alter fermentation characteristics. In Experiment 2, there were no differences in gut structure or pre-weaning and lifetime GR of pigs offered no creep feed (NC), a commercial creep feed (CF) or an ‘outdoor’ mix (OM) comprising of 1 part straw, 5 parts sow feed and 25 parts of soil taken from paddocks in which OP pigs used in Exp1a and Exp1b were farrowed. However, NC pigs grew slower in the week after weaning than the other two treatments. Backfat and feed disappearance were similar for all treatments but pigs on the OM treatment had higher carcass weights and dressing percentages than pigs on the NC and CF treatments. Villus height and crypt depth were not different between treatments and, although the piglets were weaned at 28 d, villus height decreased and crypt depth increased in the week after weaning to an extent similar to that experienced by piglets weaned at 21 d in Experiment 1. Although all piglets received intramuscular injections of 200 mg iron (Fe) dextran when 1 to 2 days old, piglets offered the OM during lactation had higher serum iron and blood haemoglobin (Hb) levels than those offered NC or CF. Furthermore, half the piglets offered NC or CF had Hb levels indicative of chronic Fe deficiency anaemia. The average parity of sows used in this experiment was 6.3 litters, suggesting that piglets may have been born with low Fe stores, possibly because of low Fe stores in their dams due to sub-optimal mineral nutrition over successive parities. In summary, the findings from these experiments partly supported the general hypothesis for this thesis. Under the conditions of these experiments, access to outdoor substrates in lactation had little effect on gut structure and lifetime growth rate but increased both carcass weight and dressing percentage, whereas rearing in DL pens increased feed intake, FCR, growth rate, P2 backfat, carcass weight and dressing percentage.

Master of Science / Department of Animal Sciences and Industry / Joann M. Kouba / The objectives of these studies were to (1) characterize mare milk and fecal bacteria, and foal fecal microbiota from birth to 4 mo and (2) determine the effect of weaning and weaning method on foal fecal bacterial composition. Next generation sequencing of the V4 region of the bacterial 16S rRNA gene was performed using the Illumina Miseq according to Earth Microbiome Project protocols and sequencing data was analyzed using QIIME. In experiment 1, mare milk, mare fecal, and foal fecal samples were collected from 9 mare and foal pairs at birth (d 0), d 2, 7, and 1, 2, 3 and 4 mo. In experiment 2, 9 foals were separated into 2 treatments: abrupt (n = 5) and gradual (n = 4) weaning methods. Fecal samples were collected the day before weaning (d-1), the day of weaning (d 0) and post-weaning on d 1, 2, 3, 4, and 7. Blood was collected for analysis of cortisol concentration at 0800 h on d -1, 1, 2, and at 0800 h and 1100 h on d 0 and 4. Heart rate was recorded in 10 min intervals on the day of weaning starting 1 h before weaning to 2 h post-weaning, and again for 1 h starting 24 h after weaning. Results from experiment 1 showed newborn foal meconium and mare milk were similar in species diversity and composition; however, large shifts in composition and increases in foal fecal bacterial diversity occurred within the first week. By 1 mo, foal fecal bacterial composition did not differ in composition from mare feces at the phylum level (P = 1.0). Firmicutes, Bacteriodetes, Verrucomicrobia, and Spirochaetes were the dominant phyla found in feces of foals 1 mo and older and adult mare feces. For experiment 2, there were no differences in species diversity (P > 0.05) or separations in bacterial community structure between weaning methods or before and after weaning. There were minor shifts in relative abundance of specific phyla and genera in response to weaning. Foals in the abrupt treatment group had increased cortisol concentrations on d 1 (P < 0.05) and increased heart rate for 50 min after weaning on d 0 (P < 0.05). The foal is born with fecal microbial communities similar to milk that rapidly change during the first week of life, reaching the same composition of its dam by the first month. The foal fecal microbiota matures prior to weaning, therefore weaning did not cause drastic changes in bacterial composition. Although acute stress was increased in abruptly weaned foals, stress associated with different weaning methods did not influence the fecal microbiota within the first week post-weaning.

Yes / Objectives: Recent developments in incremental dentine analysis allowing increased temporal resolution for tissues formed during the first 1000 days of life have cast doubt on the veracity of weaning studies using bone collagen carbon (δ13C) and nitrogen (δ15N) isotope ratio data from infants. Here we compare published bone data from the well-preserved Anglo-Saxon site of Raunds Furnells, England, with co-forming dentine from the same individuals, and investigate the relationship of these with juvenile stature. The high resolution isotope data recorded in dentine allow us to investigate the relationship of diet with juvenile stature during this critical period of life. Materials and methods: We compare incremental dentine collagen δ13C and δ15N data to published bone collagen data for 18 juveniles and 5 female adults from Anglo Saxon Raunds Furnells alongside new data for juvenile skeletal and dental age. An improvement in the method by sampling the first 0.5mm of the sub-cuspal or sub-incisal dentine allows the isotopic measurement of dentine formed in utero. Results and Discussion: δ13C profiles for both dentine and bone are similar and more robust than δ15N for estimating the age at which weaning foods are introduced. Our results suggest δ15N values from dentine can be used to evaluate the maternal/in utero diet and physiology during pregnancy, and that infant dentine profiles may reflect diet PLUS an element of physiological stress. In particular, bone collagen fails to record the same range of δ15N as coforming dentine, especially where growth is stunted, suggesting that infant bone collagen is unreliable for weaning studies. / Funded in part by the NERC standard grant NE/F018096/2; University of Bradford.

The effects of weaning stressors on several immune and health responses were measured in three experiments. Sixty-four beef calves from 2 sources were bled on d - 7 (pre-weaning), 0 (weaning), 7, 14, and 21 (post-weaning). Serum selenium (Se), neutrophil and lymphocyte counts, and glutathione peroxidase (GSH-Px) activity for erythrocytes and leukocytes were measured for each calf at each date. Erythrocyte GSH-Px activity remained constant over time, while leukocyte GSH-Px and serum Se increased on d 7 (P<0.0001). Effects of single mineral vs. multi-mineral supplementation were measured for several immune and health responses in 2 trials. Trial 1: 36 heifers weaned on-site at SVAREC were randomly assigned 1 of 2 dietary supplements: 1) no supplement; 2) 15% CP at 0.5% BW; and 1 of 3 injection treatments: 1) no treatment (control); 2) Mu-Se injection; 3) Multi-Min injection. Whole blood Se and serum Cu increased post-weaning and serum Zn decreased post-weaning. Mu-Se-supplemented heifers gained weight faster between d 14-28 vs. Multi-Min-supplemented (P=0.01) or control heifers (P=0.02). Trial 2: 48 steers purchased at auction and transported to SVAREC were randomly assigned to 1 of 4 pasture management systems: 1) control (no treatment); 2) litter fed; 3) litter applied; 4) inorganic fertilizer; and 1 of 3 injection treatments (same as Trial 1). Whole blood Se and serum Cu increased post-stress and serum Zn decreased post-stress. Oxidative burst activity decreased in Mu-Se and Multi-min supplemented steers between d 0-4 vs. control steers (P<0.01). Multi-min-supplemented steers had higher phagocytic activity vs. steers in either Mu-Se or control groups (P=0.04). / Master of Science

The beef cattle marketing structure imposes stress on calves due to weaning, transport, commingling, and adaptation to new diets, resulting in a weakened immune systems at the height of disease risk, frequently causing bovine respiratory disease. Backgrounding programs facilitate opportunities for calves to overcome stressors by building immunity, and adapting the rumen to high concentrate diets for improved feedlot performance. Four experiments were conducted to compare backgrounding strategies and effects of supplementation frequency performance and the effects of the ruminal environment. In Exp. 1, 48 weaned steers were used to investigate the effects of transportation and supplementation frequency, while in Exp. 2, 36 heifers were used to investigate only supplementation frequency. No differences in gains were observed due to transportation stress or supplementation frequency. Weaning stress resulted in elevated (P < 0.05) creatine kinase and neutrophil:lymphocyte ratios during the first week. In Exp. 3, 48 calves were used to compare the effect of tall fescue type on performance and health. Calves on novel endophyte fescue had higher ADG (P = 0.07) than on endophyte-infected fescue. Experiment 4 investigated the changes in ruminal environment due to supplementation frequency. No differences were observed between supplementation frequencies for ruminal pH, ammonia, or VFA concentration, and DM, or CP digestibility. Therefore, the rumen maintained a hospitable environment to promote bacterial protein synthesis and fiber digestion with every 48 h supplementation. Backgrounding calves with high fiber co-product supplements or on novel endophyte fescue can enhance calf performance. / Master of Science

Beef cattle producers continuously search for nutritional management options that provide flexibility to production scenarios. Due to its positive effects on maternal productivity, early weaning is one such alternative strategy that has received considerable interest. To better understand the effects of early weaning on calf productivity, an extensive literature review and three experiments were conducted to evaluate the effects of early weaning on finishing feed efficiency, marbling development and retail product quality of beef steers. In experiment I, which included 90 Angus-sired steers from four calving seasons, early weaning followed by a short ad libitum concentrate-feeding and pasture-backgrounding phase reduced finishing residual feed intake (RFI) by 7 % (P < 0.0001) and increased carcass marbling score (MS) by 10 % (P < 0.01) when compared to conventionally weaned (CW) contemporaries. Similar effects were observed in experiment II, which included 28 Angus and Simmental-sired steers, as early weaning reduced RFI (P < 0.01) and increased carcass MS (P < 0.01). Lung mass of early weaned (EW) steers was greater than their CW contemporaries (P < 0.05), and was inversely related to RFI (R2 = 0.17; P < 0.05). Finishing treatments in this experiment included a high corn ration and an alternative low corn ration that iso-calorically replaced 50 % of the DM from corn with dried corn gluten feed. Iso-caloric replacement of corn reduced lung mass (P < 0.01), and when combined with the observed increase of EW steers suggests that lung development is affected by dietary energy type at various stages of growth. In experiment III, objective analyses of ribeye steaks obtained from steers included in experiment two revealed that early weaning increased cross-sectional muscle fiber area by 28 % (P < 0.001) and tended to increase (P = 0.08) Warner-Bratzler shear force by 36 %. Nonetheless, these effects were not great enough to alter un-trained consumer perception of texture (P ≥ 0.65), juiciness (P ≥ 0.55), flavor (P ≥ 0.25) or overall acceptability (P ≥ 0.34). Collectively, these results indicate that early weaning enhances finishing feed efficiency and carcass marbling without affecting un-trained consumer sensory perception. / Ph. D.

The objective of this study was to assess the effect of low stress (LS) handling of beef calves on weight gain and calf activity associated with the weaning process. Cattle were of Angus and Angus cross breeding from two separate herds in Virginia. Handlers for the LS groups went through a short training session. Handlers for the Control (C) groups did not have any special training and handled their group as they would have with no adjustments. Handling and calf activity were monitored each time (6 times) the cows were worked from calving through one month post-weaning. Weights were taken from birth to one month post-weaning. During the week post-weaning the C calves averaged a gain of 4.38 lbs. and the LS calves averaged a gain of 16.94 lbs. One month post-weaning the C calves averaged a gain of 49.01 lbs., while the LS calves averaged a gain of 68.6 lbs. This showed a difference (p < 0.0001) between handling method for weight gain in calves for one week and one month post-weaning. Pedometers were used to assess calf activity post-weaning. Steps per hour (SPH) for the week post-weaning was numerically higher for those calves handled conventionally and not trained for weaning. The C calves averaged 1048 to 1629 SPH for the first three days, where the LS calves averaged 443 to 644 SPH for the first three days. Additionally, the artificial insemination conception rates (AICR) were calculated in each herd and treatment groups compared, however results were equivocal. This study demonstrated that handling cattle using low stress techniques can make significant improvements with regard to weaning weights and has potential to increase other areas of production in beef cattle. / Master of Science

Yes / Mothers' responsiveness to hunger and fullness cues has been implicated in the development of infant over-weight, and baby led weaning (BLW) is argued to be one way to protect against overfeeding. Whilst studies have examined maternal perceptions of hunger, fullness and adequate intake to some degree in traditional weaning (TW) contexts, less is known about this in BLW. This study therefore aimed to understand and compare maternal perceptions of cues and intake in BLW and TW. Eleven mothers of infants (7–24m) participated in semi-structured interviews based on discussions of short videos featuring participants feeding their infants. Interviews were read and transcribed in full. Data were selected for coding which addressed mothers' perceptions of infant hunger, fullness and sufficient consumption and subsequently subjected to template analysis. A sample of data was coded to produce an initial template which was applied to all interviews and revised in an iterative process to produce a final template for interpreting findings. Mothers in the study were adept at recognising fullness cues and gauging feeding state. Both groups perceived similar hunger cues although TW mothers reported a wider range of fullness cues. Both groups used numerous strategies for judging the adequacy of their babies’ intake. These included the use of infant cues, however perceived adequacy of intake was also influenced by factors such as infant tiredness and maternal worries about over and under-eating. Findings have implications for the development of responsive feeding interventions while also highlighting the utility of video elicited interviews for understanding feeding interactions. / This work was supported by a White Rose Doctoral Training Partnership Economic and Social Research Council PhD studentship (UK) to Janet McNally.

Background: The adverse effects of mechanical ventilation (MV) are a major health concern associated with poor outcomes and economic burden. Some populations, such as those requiring more than one attempt at the gradual removal of MV (weaning), are at risk for longer duration of MV and associated complications. Traumatically injured patients have a higher prevalence of positive illicit drug toxicology then the general population. The traumatically injured, positive for illicit drugs who requires MV, may experience the sequelae of withdrawal syndrome and violate the thresholds that allow weaning, leading to longer durations MV. Methods: A retrospective descriptive analysis of a convenience sample of 52 adult trauma patients from SJHMC admitted between January 1 to December 31, 2014 who presented positive for illicit drugs and required mechanical ventilation. This sample was analyzed to: 1) describe the characteristics of this specific sample, 2) determine the prevalence of a difficult-to-wean subsample, 3) describe the characteristics of this sample during weaning attempts, and 4) determine if the existing weaning protocol necessitates amending. Results: Samples ability to wean; 78.8% (n=41) simple weaning; 15.38% (n=8) difficult weaning; and 5.77% (n=3) prolonged. Zero cases of adverse effects of MV or withdrawal syndrome detected. There was no correlation between stimulant and/or depressant and ability to wean (p=0.662). There was no relationship between injury severity score (ISS) and weaning group (p=0.762). Characteristics identified included; male to female ratio 4:1 and majority with ISS score>24. Variables within weaning protocol were missing 25-84% of data. Conclusion: The ability to wean MV in this sample is similar to what is reported in the general population, suggesting that they are not at risk for difficult weaning or prolonged MV. This sample’s majority was comprised of more traumatically complex, young males than found in the general trauma population. Investigators were unable to analyze or amend the current protocol because of the large amounts of missing data indicating possible gaps in adherence and/or documentation. To our knowledge, this is the first project that describes ability to wean in the traumatically injured positive for illicit drug.

There is sparse research literature in agricultural economics regarding early weaning as a potential alternative production/marketing strategy. The objective of this research is to estimate and analyze the impacts on net returns of alternative weaning dates for Tennessee cow-calf operations including alternative post-weaning treatments for calves. The Decision Evaluator for the Cattle Industry (DECI) simulation program was used for this study to produce outputs such as calf numbers, gender, and weights, other output including cow weights and body condition score, both at calving and at weaning, and pregnancy percentages. Forty-two simulations were run for average and summer drought weather, weaning at an average age of 135, 165, 195, 225, 255, and 285 days and selling at weaning or after a 60 or 90-day drylot backgrounding period. Prices for steers, heifers, and culled cows from 1995-2008 were taken from market reports. Costs were derived from University of Tennessee Extension Beef and Forage Budgets and USDA-NASS. The outputs from DECI were combined with prices to result in total revenues. Subtracting the costs of feed, interest, veterinary and medical, and marketing resulted in return to land, labor, management, and risk to the enterprise. The results of this study revealed that under average weather conditions in East Tennessee, marketing at weaning in November yielded the highest net return. Weaning in August and backgrounding for 60 days yielded the lowest net return with the base 90-cow herd. Under summer drought conditions, marketing at weaning in August resulted in the highest net return. Weaning in November and marketing after a 90-day backgrounding period yielded the lowest net return. Under the conditions used in this study, the only time early weaning makes economic sense is when herd size is increased for June or July weaning or under drought conditions when August (195 days) weaning and sale is optimal. Several limitations of this study imply that additional research is required on this topic before definite conclusions can be drawn.