LP Females Research Articles

L-β-aminoisobutyric acid, L-BAIBA, a marker of bone mineral density and body mass index, and D-BAIBA of physical performance and age

As both L- and D-BAIBA are increased with exercise, we sought to determine if circulating levels would be associated with physical performance. Serum levels of L- and D-BAIBA were quantified in 120 individuals (50% female) aged 20–85 years and categorized as either a “low” (LP), “average” (AP) or “high” performing (HP). Association analysis was performed using Spearman (S) and Pearson (P) correlation. Using Spearman correlation, L-BAIBA positively associated with (1) body mass index BMI (0.23) and total fat mass (0.19) in the 120 participants, (2) total fat mass in the 60 males (0.26), and (3) bone mineral density, BMD, (0.28) in addition to BMI (0.26) in the 60 females. In HP females, L-BAIBA positively associated with BMD (0.50) and lean mass (0.47). D-BAIBA was positively associated with (1) age (P 0.20) in the 120 participants, (2) age (P 0.49) in the LP females and (3) with gait speed (S 0.20) in the 120 participants. However, in HP males, this enantiomer had a negative association with appendicular lean/height (S − 0.52) and in the AP males a negative correlation with BMD (S − 0.47). No associations were observed in HP or AP females, whereas, in LP females, a positive association was observed with grip strength (S 0.45), but a negative with BMD (P − 0.52, S − 0.63) and chair stands (P − 0.47, S − 0.51). L-BAIBA may play a role in BMI and BMD in females, not males, whereas D-BAIBA may be a marker for aging and physical performance. The association of L-BAIBA with BMI and fat mass may reveal novel, not previously described functions for this enantiomer.

191-LB: Artesunate Treatment Improves Hyperglycemia in a Rodent Model of Gestational Glucose Intolerance without Increasing Beta-Cell Mass

Gestational diabetes (GDM) has been associated with a failure to adequately increase maternal β-cell mass (BCM) during pregnancy. The anti-malarial drugs, artemisinins, have been shown to improve glucose homeostasis in rodent models of diabetes by increasing BCM. Our objective was to reverse BCM deficiency and impaired glucose tolerance in a mouse model of GDM using the artemisinin artesunate. In order to produce glucose intolerance in pregnancy, female mice (F0) were fed a low protein (8%, LP) diet during gestation and lactation, and offspring weaned onto control (20%, C) diet. At 6-10 weeks age female offspring (F1) were time-mated and given C diet throughout pregnancy. Artesunate was administered via drinking water from gestational day (GD) 0.5-6.5. We previously found glucose intolerance, mimicking aspects of GDM, in LP-exposed offspring at GD18 when compared to animals fed a C diet. Thus, glucose tolerance tests (GTT) were performed at GD18 or for non-pregnant age-matched animals. Subsequently, pancreata were removed for fluorescence immunohistochemistry to assess histology. Artesunate-treated LP females had a lower area under the curve during a GTT (389.9±52.3mmol/L*min) compared to non-treated LP females at GD18 (726.6±56.9mmol/L*min, p<0.01). Furthermore, artesunate-treated LP females had improved glucose homeostasis at 5min (9.1 vs. 18.9mmol/L), 15min (11.6 vs. 20.9mmol/L) and 30min (10.2 vs. 19.2mmol/L) during the GTT compared to non-treated LP females at GD18 (p<0.05). There were no significant differences in BCM, alpha-cell mass, or mean islet size between LP and artesunate-treated LP females at GD18. The results show that artesunate-treated LP pregnant females had significantly improved glucose homeostasis compared to untreated LP mice at GD18. However, the improved glucose tolerance was not associated with increased BCM or changes in endocrine pancreas morphology. Disclosure S. Szlapinski: None. D.J. Hill: None. Funding St. Joseph's Health Care Foundation; Ontario Graduate Scholarship

Long-term implications of feed energy source in different genetic types of reproductive rabbit females: I. Resource acquisition and allocation

To achieve functional but also productive females, we hypothesised that it is possible to modulate acquisition and allocation of animals from different genetic types by varying the main energy source of the diet. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66), a maternal line characterised by hyper-prolificacy; LP (n=67), a maternal line characterised by functional hyper-longevity; R (n=79), a paternal line characterised by growth rate. Females were fed with two isoenergetic and isoprotein diets differing in energy source: animal fat (AF) enhancing milk yield; cereal starch (CS) promoting body reserves recovery. Feed intake, weight, perirenal fat thickness (PFT), milk yield and blood traits were controlled during five consecutive reproductive cycles (RCs). Females fed with CS presented higher PFT (+0.2 mm, P<0.05) and those fed AF had higher milk yield (+11.7%, P<0.05). However, the effect of energy source varied with the genetic type and time. For example, R females presented a decrease in PFT at late lactation (−4.3%; P<0.05) significantly higher than that observed for H and LP lines (on av. −0.1%; P>0.05), particularly for those fed with AF. Moreover, LP females fed with AF progressively increased PFT across the RC, whereas those fed with CS increased PFT during early lactation (+7.3%; P<0.05), but partially mobilised it during late lactation (−2.8%; P<0.05). Independently of the diet offered, LP females reached weaning with similar PFT. H females fed with either of the two diets followed a similar trajectory throughout the RC. For milk yield, the effect of energy source was almost constant during the whole experiment, except for the first RC of females from the maternal lines (H and LP). These females yielded +34.1% (P<0.05) when fed with CS during this period. Results from this work indicate that the resource acquisition capacity and allocation pattern of rabbit females is different for each genetic type. Moreover, it seems that by varying the main energy source of the diet it is possible to modulate acquisition and allocation of resources of the different genetic types. However, the response of each one depends on its priorities over time.

Long-term implications of feed energy source in different genetic types of reproductive rabbit females: III. Fitness and productivity

The specialization process associated with genetic selection could be associated with functional disorders, affecting the reproductive success of females (fitness). We hypothesized that by modulating energy acquisition and allocation of females we could balance productivity and reproductive success. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66) maternal line specialized in prolificacy, LP (n=67) generalist maternal line, R (n=70) paternal line specialized in growth rate. We fed each genetic type with two diets specifically designed to promote milk yield (AF) or body reserves recovery (CS). We controlled females between their first and fifth reproductive cycles, recording traits related with productivity and fitness of females. H females fed CS had on average 11.2±0.43 kits with an individual weight of 54±1.2 g at birth and 525±11 g at weaning. Their conception rate when multiparous was 44% and their survival rate at the end of the experiment 30%. When they were fed AF, the individual weight of kits was 3.8 g heavier (P<0.05) at birth and 38 g heavier at weaning (P<0.05), the conception rate when multiparous increased 23 percentage points (P<0.05) and the survival rate at the end of the experiment 25 percentage points (P<0.05). LP females fed CS had on average 10.8±0.43 kits with an individual weight of 52±1.2 g at birth and 578±11 g at weaning. Their conception rate when multiparous was 79% and their survival rate at the end of the experiment 75%. When they were fed AF, it only increased individual weight of kits at weaning (+39 g; P<0.05). R females fed CS had on average 8.4±0.43 kits with an individual weight of 60±1.2 g at birth and 568±11 g at weaning. Their conception rate when multiparous was 60% and their survival rate at the end of the experiment 37%. When they were fed AF, they presented 1.4 kits less at birth (P<0.05) but heavier at birth (+4.9 g; P<0.05) and at weaning (+37 g; P<0.05). Therefore, we observed that genetic types prioritized different fitness components and that diets could affected them. In this sense, seems that more specialized genetic types, were more sensitive to diets than the more generalist type.

Patterns of body condition use and its impact on fertility

&lt;p&gt;A total of 60 nulliparous crossbred rabbit females were, a posteriori, divided into 2 experimental groups according to their natural “decision” to conceive or not at day 11 post first parturition (L: solely-lactating or LP: lactating-pregnant). This design allowed us to study the evolution of body reserves around first parturition and its influence on the future reproductive success of rabbit females. Primiparous rabbit females that failed to conceive when inseminated at day 11 post-partum (L) seemed to have a higher perirenal fat thickness (PFT) 12 d pre-partum (+0.25 mm; P=0.079) than females that conceived (LP). In the subsequent days, L females showed a significantly higher mobilisation rate than LP females (on av.–0.12 and –0.07 mm of PFT per day, respectively; P=0.007), reaching a lower PFT at partum (5.17 mm vs. 5.62 mm, respectively; P = 0.002). However, due to a greater recovery rate observed in L females (+0.15 vs. +0.08 mm of PFT per day for L and LP females, respectively; P=0.007), PFT at 10 d post-partum was similar (on av. 5.86 mm). These different patterns showed that PFT level at 12 d pre-partum and PFT mobilisation rate onwards seems to drive the start of a new pregnancy. It also seems to modify the energy metabolism of rabbit females, allowing does to recover perirenal fat tissue without compromising the production of milk necessary for the current litter.&lt;/p&gt;

Comparison of immune response to lipopolysaccharide of rabbit does selected for litter size at weaning or founded for reproductive longevity

To evaluate differences in maternal lines to the immune response of reproductive rabbit does, a total of 64 animals of two different lines: (1) founded for hyper-longevity and litter size criteria (LP) and (2) selected for litter size at weaning (V) were used. Females were subjected to three different reproductive efforts: post-partum (PP) mating at first lactation and 9 kits during the second; post-weaning (PW) mating at first lactation and 9 kits during the second; and PW mating at first lactation and 5 kits during the second. At second weaning (30days PP), an acute response was induced by intravenous infusion of lipopolysaccharide (LPS). LP females seemed to be lower affected during the hyper-acute phase than V females, showing lower plasma glucose content at 1.5h post infusion (pi) and rectal temperature at 6hpi; and showed higher ulterior immune response, with higher levels of C-reactive protein at 48hpi and haptoglobin in plasma from 24hpi. Survival test conferred a higher risk of culling for V than for LP females during the first hours after challenge. These results may suggest that, regarding immune response to LPS challenge, foundation by hyper-longevity productive criteria lead to obtain a more robust population of rabbit does, characterized by improved response ability.

Digestive efficiency in rabbit does according to environment and genetic type

Ninety lactating rabbit does of three different genetic types [2 from a line differentiating 20 generations by selection for litter size at weaning (lines V16 and V36) and 1 from a line founded under reproductive longevity criteria and then selected by litter size at weaning (line LP)] were subjected to three environmental conditions: NC, females housed under normal conditions (14 to 20 o C) and fed with a control diet (333 g NDF/kg DM); HC, females housed under heat conditions (25 to 35 o C) and fed with the control diet; or NF, females housed under normal conditions and fed with a fibrous diet (443 g NDF/kg DM). The apparent digestible coefficients of dry matter (DMd), organic matter, crude protein (CPd), gross energy, NDF (NDFd) and acid detergent fibre, as well as the daily intake of dry matter (DM), digestible protein (DP) and digestible energy (DE), were determined (14 to 18 d post-partum). The environment affected all variables analysed. In general, heat conditions reduced the daily feed intake (around -30%; P<0.05) and increased main apparent digestible coefficients (+4.5 percentage points for DMd). In contrast, the use of a fibrous diet led to lower DE intake (-217 kJ/d; P<0.05) and main apparent digestibility coefficients (-13.5 percentage points for DMd). Females from line V, regardless of generation, showed lower daily DM intake (-19.2 g/d; P<0.05) and NDFd (-1.5 percentage points; P<0.05) than line LP. Interactions between genetic type and environment were found for daily DM intake, NDFd and CPd. When receiving fibrous diet, LP females showed a higher increment in daily DM intake (65.6 g/d; P<0.05) than V36 females, compared to control. Under heat conditions, NDFd obtained for LP females were higher to those in normal conditions (+3.14 percentage points), while V females showed similar NDFd. In addition, the increase in CPd observed under heat conditions was higher for LP (+9.87 percentage points) and V36 (+8.74 percentage points) than V16 females (+3.84 percentage points). In conclusion, rabbit females from a line founded for reproductive longevity seem to show a higher flexibility in their digestive capacity under constrained conditions.

Maternal Low-Protein Diet Induces Gender-Dependent Changes in Epigenetic Regulation of the Glucose-6-Phosphatase Gene in Newborn Piglet Liver1–3

Glucose-6-phosphatase (G6PC) plays an important role in glucose homeostasis because it catalyzes the final steps of gluconeogenesis and glycogenolysis. Maternal malnutrition during pregnancy affects G6PC activity, yet it is unknown whether epigenetic regulations of the G6PC gene are also affected. In this study, we fed primiparous, purebred Meishan sows either standard-protein (SP; 12% crude protein) or low-protein (LP; 6% crude protein) diets throughout gestation and analyzed hepatic G6PC expression in both male and female newborn piglets. The epigenetic regulation of G6PC, including DNA methylation, histone modifications, and micro RNA (miRNA), was determined to reveal potential mechanisms. Male, but not female, LP piglets had a significantly lower serum glucose concentration and greater hepatic G6PC mRNA expression and enzyme activity. Also, in LP males, glucocorticoid receptor binding to the G6PC promoter was lower compared with SP males, which was accompanied by hypomethylation of the G6PC promoter. Modifications in histones also were gender dependent; LP males had less histone H3 and histone H3 lysine 9 trimethylation and more histone H3 acetylation and histone H3 lysine 4 trimethylation on the G6PC promoter compared with the SP males, whereas LP females had more H3 and greater H3 methylation compared with their SP counterparts. Moreover, two miRNA, ssc-miR-339–5p and ssc-miR-532–3p, targeting the G6PC 3' untranslated region were significantly upregulated by the LP diet only in females. These results suggest that a maternal LP diet during pregnancy causes hepatic activation of G6PC gene expression in male piglets, which possibly contributes to adult-onset hyperglycemia.

How selection for reproduction or foundation for longevity could have affected blood lymphocyte populations of rabbit does under conventional and heat stress conditions

The present work characterises how selection for reproduction (by comparing two generations – 16th and 36th – of the V line selected for litter size at weaning) or foundation for reproductive longevity (the LP line) can affect the blood lymphocytes populations of reproductive rabbit does under normal [conventional housing, average daily minimum and maximum temperatures of 14°C and 20°C, respectively] and heat stress conditions [climatic chamber, 25°C and 36°C] from the first to the second parturition. Housing under heat stress conditions significantly reduced the B lymphocytes counts in female rabbits (−34×106/L; P<0.05). The highest lymphocytes population value in blood (total, T CD5+, CD4+ and CD8+) was noted at the first parturition, while the B lymphocytes count was significantly lower at the second parturition (−61×106/L; P<0.05). Selection for litter size at weaning (V females) reduced the average counts of total and B lymphocytes in blood (−502 and −60×106/L, respectively; P<0.01), mainly because these populations in V36 females continuously lowered from the first to the second parturition under normal housing conditions. Thus, more selected females (V36) at the second parturition showed significantly lower counts in blood for total, T CD5+ and CD25+ lymphocytes (−1303, −446 and −33×106/L, respectively; P<0.05). The main differences in blood counts between V36 and V16 females disappeared when housed under heat stress conditions, except for T CD5+ and CD25+, which significantly increased (T CD5+: +428×106/L; CD25+: +41×106/L; P<0.01) in the V16 vs. V36 females on day 10 post-partum. Under normal conditions, no differences between LP and V36 females were found for most lymphocyte populations; only higher counts were noted in CD25+ (+20×106/L; P<0.05) for LP females. However, the lymphocytes counts [especially total (+1327×106/L; P<0.01) and T CD5+ (+376×106/L; P<0.10)] of LP females increased under heat vs. normal conditions when lymphocytes populations presented the lowest values (second parturition), while V36 females’ counts remained invariable. Positive correlations were found between feed intake (r=+0.51; P<0.001) and females’ perirenal fat thickness (r=+0.40; P<0.001) with B lymphocytes counts in the blood of primiparous rabbit females in the week 2 of lactation. These results indicate that selection for litter size at weaning might diminish their immune system's response and adaptation capacity, while the foundation for reproductive longevity criteria leads to more robust rabbit females as they present greater modulation under heat stress conditions when the immune system is affected.

Constitution and evaluation of a long-lived productive rabbit line1

An evaluation of a new maternal line (LP) of rabbits was carried out. This new line was founded following a scheme similar to that applied in the selection for hyperprolificacy in rabbits or pigs. In this case, the selection criteria were hyperlongevity and an independent culling level near the average for prolificacy. Evaluation was carried out by comparison of the reproductive and longevity performance of the LP line with another maternal line recognized for good reproductive performance and standard longevity (V line). The results indicate that the LP line could be a valuable resource for inclusion in the current 3-way cross schema used in rabbit production, because females showed better survival ability and nearly the same prolificacy as the well-reputed V line. A V doe was 1.3 times more likely to leave the herd than an LP doe, and the probability of the differences in prolificacy between lines being greater than 0 was not extreme (no more than 0.22). Differences in relative performance of the lines were observed across farms for prolificacy, longevity, cumulative production, and fertility; however, based on deviance information criterion results, the data supported the hypothesis of only these differences being generated under a genotype x environment interaction for prolificacy traits. The longer productive life of LP females could partially be understood as an indication of success of the selection procedure during the foundation of this line.

The role of prolactin and testosterone in mediating seasonal differences in the self-grooming behavior of male meadow voles, Microtus pennsylvanicus

Self-grooming in response to the odors of conspecifics is a form of olfactory communication among meadow voles. The amount of time meadow voles spend self-grooming when they encounter the odors of conspecifics varies seasonally, with males targeting the odors of reproductively active females only during the breeding season. Other odor related behaviors in male voles such as odor preferences for conspecifics and the attractiveness of their odors to conspecifics vary seasonally as well. For male meadow voles, these behaviors are mediated by seasonal variations in testosterone (T) and prolactin (PRL) titers. The objective of this study was to determine whether seasonal differences in the amount of time male meadow voles self-groom in response to odors of conspecifics are mediated by seasonal rhythms in their circulating T and PRL titers. We tested the hypothesis that high titers of both T and PRL are necessary for reproductively active (long-photoperiod; LP) males and sufficient for reproductively quiescent (short-photoperiod; SP) male voles to spend more time self-grooming in response to odors of LP females than to those of other conspecifics. Results of this study demonstrate that high titers of PRL and T are necessary for LP male meadow vole to self-groom more in response to odors of LP females as compared to those of other conspecifics, but were not sufficient to induce SP males to preferentially self-groom to odors of LP females. The endocrine control of self-grooming by LP males appears to depend upon high titers of both PRL and T, which matches the endocrine mediation of other odor related behaviors in male voles. In contrast, the endocrine tissues that underlie self-grooming in SP male meadow voles appear to be refractory to the effects of LP-equivalent titers of PRL and T.

The effect of divergent selection for total plasma phosphorus in Japanese quail on fearfulness and selected blood and heart parameters

A selection experiment utilizing Japanese quail was initiated to study the genetic relationship of growth and reproduction traits. In this study, lines were selected for increased (HP line) and decreased (LP line) total plasma phosphorus at the beginning of lay. The HP and LP lines were derived from a randombred control population (R1 line) that was maintained with the selected lines to remove environmental variation over generations. During the course of selection, it was observed that blood from HP line females was more viscous than that of the LP and R1 females. In later generations of selection, mortality of females during a 120-d egg production period was higher in the HP line than in the LP and R1 lines. The purpose of this experiment was to identify possible factors contributing to the increased mortality in the HP line. Fearfulness, as measured by tonic immobility, was greater in the HP and LP lines than in the R1 line. Indirect blood pressure measurements were made near the beginning and near the end of the 120-d egg production period. No significant line differences were observed in either measurement. Weight of the heart at the end of the laying period was higher in the HP and LP lines than in the R1 line. Histological study of the hearts of the HP and R1 lines indicated significant increases in the HP line in collagen content of the coronary arteries and in myocardial fibrosis. The data suggest that the increased mortality of females of the HP line relative to the R1 line during the laying period may be related to increased fearfulness and changes in the coronary structure leading to heart abnormalities.

Long day lengths enhance myelination of midbrain and hindbrain regions of developing meadow voles

Rates of brain growth differed in meadow voles maintained in long (LP) or short (SP) photoperiods postnatally. At 35 days of age, brain weight was greater by 6.6% in LP males and by 4.7% in LP females as compared to their SP counterparts. Whole brain galactolipid content, an index of brain myelin, was greater by 15.6% in LP as compared to SP males. At 70 days of age, brains of LP males were 4% heavier than those of SP males. Differences attributable to photoperiod were most pronounced in midbrain and hindbrain (8% and 14%, respectively). DNA and galactolipid contents were greater by 11% and 15%, respectively, in hindbrain of LP males. Photoperiod did not affect any of these measures in diencephalon, striatum, or cerebellum. Short day lengths reduce myelination in meadow voles, presumably by decreasing proliferation rates of oligodendroglia. This is one facet of a general delay in somatic development associated with being born at the end of the normal breeding season when day lengths are decreasing or below a critical threshold.

Correlated response in reproduction, growth and composition to selection in gilts for extremes in age at puberty and backfat

Females ( n=50) were selected for extremes in early vs. late sexual maturity (12 EP, 13 LP) based on age at first detectable estrus; or, high vs. low backfat (13 HF, 12 LF) based on backfat at the tenth rib adjusted to 105 kg basis. These selected females were then heat checked daily, bred during scheduled breeding periods and allowed to farrow. Reproductive performance was then monitored. More EP than LP females demonstrated a normal cycling pattern. Also, more HF than LF females had normal cycling patterns. Early puberty (EP) female farrowed more litters per sow ( P < 0.05) and more pigs per litter ( P < 0.10) than LP. Low-fat females farrowed fewer pigs alive ( P < 0.10) than HF. Early puberty (EP) and HF females had the highest Sow Productivity Indexes (SPI), while LP females were intermediate. Low-fat females had the lowest SPI ( P < 0.05). These results indicate that single-trait selection for extreme leanness or late puberty could be detrimental to reproductive performance. Progeny (371 gilts and 173 barrows) from these litters were then performance tested. The correlated responses in the offspring to selection for extremes for puberty in the dams indicates that selection for early puberty in the females will result in faster gaining offspring with an increased amount of backfat. The correlated responses in offspring of the backfat lines indicates that selection for low backfat thickness in cycling females will decrease fat and increase the amount of lean deposited by her offspring. Also, LF offspring reached puberty and market weight at an earlier age.

Effects of Low and High Protein Diets on the Induction of Microsomal Drug-metabolizing Enzymes in Rat Liver

To determine the effect of low and high levels of dietary proteins plus low doses of phenobarbital (PB) on the induction of drug-metabolizing enzymes, weanling male and female Sprague-Dawley rats were fed, ad libitum, diets containing 3.5 (low protein, LP), 26 (normal protein, NP), and 42% (high protein, HP) casein for 33 days. Five animals from each dietary group were injected with 10 mg of PB/kg body weight, intraperitoneally, for the last 3 days of the experimental period. The 10,000 X g supernatant and microsomes were prepared from perfused livers from each group. Both LP and HP diets caused a significant decrease in the activity of biphenyl 4-hydroxylase, an increase in the activity of p-nitrobenzoate reductase, and no changes in the activities of 4-methylumbelliferone glucuronyltransferase and cytochrome P-450. The low doses of PB used in this study caused significant induction of cytochrome P-450 (P less than 0.10), biphenyl 4-hydroxylase, and p-nitrobenzoate reductase (except in LP and NP females). The males of NP and HP groups had consistently higher activities of these enzymes than corresponding females, however, this sex difference in the first two enzymes was abolished by feeding of the LP diet.