Impact of diet deprivation and subsequent over-allowance during prepuberty. Part 1. Effects on growth performance, metabolite status, and mammary gland development in gilts

The impact of diet deprivation and subsequent over-allowance on the metabolite status, mammary development, and mammary gene expression in prepubertal gilts was determined. Forty-seven gilts were reared under a conventional (control, CTL; n = 23) or an experimental (treatment, TRT; n = 24) dietary regimen. The later regimen (consisting of diet deprivation and subsequent over-allowance) provided 70 (restriction diet, RES) and 115% (over-allowance diet, OVER) of the protein and DE contents provided by the CTL diet. Experimental diets were fed ad libitum starting at 27.7 ± 3.4 kg of BW as follows: 3 wk RES, 3 wk OVER, 4 wk RES, and 4 wk OVER. At each diet change, BW and individual feed intakes were measured, and blood samples for metabolite and IGF-I assays were obtained. Some gilts (11 CTL and 12 TRT) were slaughtered on d 235 (after reaching puberty) to collect mammary tissue for compositional analyses and measures of gene expression. Body weight gain (P < 0.01) and G:F (P < 0.05) of gilts were reduced during each period with the RES diet; however, there was no compensatory growth during the periods when the OVER diet was fed. Feeding the RES diet reduced concentrations of urea and IGF-I (P < 0.01) and feeding the OVER diet increased FFA (P < 0.01) and glucose (P < 0.10) in TRT gilts compared with CTL gilts. The TRT gilts had less parenchymal tissue (P < 0.05) and tended to have less total parenchymal fat and protein (P < 0.10) than CTL gilts. The mammary mRNA relative abundance of the signal transducers and activators of transduction 5B was decreased in TRT compared with CTL gilts (P < 0.05). In conclusion, the diet deprivation and over-allowance regimen used in the growing-finishing period did not have beneficial effects on mammary development after puberty. In fact, a detrimental effect was observed.

Effect of supplementing the diet of lactating sows with NuPro® on sow lactation performance and piglet growth

Plante, P. A., Laforest, J.-P. and Farmer, C. 2011. Effect of supplementing the diet of lactating sows with NuPro® on sow lactation performance and piglet growth. Can. J. Anim. Sci. 91: 295–300. The impact of supplementing the diet of lactating sows with NuPro® (a source of yeast-derived proteins) on their performance and that of their piglets was studied. Treatments were: control (CTL, n=22), 30 g of NuPro per day (NuPro30, n=22), and 60 g of NuPro per day (NuPro60, n=21). The NuPro was mixed daily with 500 g of feed and provided over a 21-d lactation. Jugular blood samples were obtained from sows on days 2, 7 and 20 of lactation to measure urea concentrations. Milk samples were obtained on days 7 and 20 of lactation for compositional analyses and quantification of 5′ monophosphate nucleotides. Litter size was standardized to 10±1 at 48 h postpartum. Sow body weight loss and backfat loss during lactation were recorded, as well as the weights of piglets until day 56. Feed intakes of sows during lactation and of piglets for 5 wk post-weaning were noted. Statistical analyses were performed with PROC MIXED using an analysis of variance with one factor (three levels) according to a completely randomized design. None of the animal performance data differed among treatments (P>0.1). Standard milk composition was also similar across treatments (P>0.1). Concentrations of nucleotides in milk were greater on day 7 than on day 20 of lactation (P<0.001) but were not affected by treatments (P>0.1). In conclusion, supplementing the diet of lactating sows with NuPro did not increase nucleotide concentrations in milk and had no beneficial effects on sow or piglet performances.

Farrowing induction induces transient alterations in prolactin concentrations and colostrum composition in primiparous sows

Hormonal changes involved in the farrowing process partly control the initiation of lactation. Inducing farrowing by injection of PG may alter the normal prepartum hormonal cascade. The aim of the study was to investigate the consequences of farrowing induction on colostrum yield and composition, as well as newborn piglet growth. Gilts were treated with 2 mg of alfaprostol on d 113 of gestation (induced farrowing, IF, n = 9) or were injected with 1 mL of a saline solution (natural farrowing, NF, n = 11). Colostrum production was estimated during 24 h, starting at the onset of parturition, based on piglet BW gains. Colostrum samples were collected during the 36 h after the onset of parturition. Blood samples were collected from sows as of d 112 of pregnancy until d 2 postpartum (d 0 being the day of parturition). Piglet blood samples were obtained at birth, on d 1, and on d 21. Litter size and litter weight at birth did not differ between groups (P > 0.10). Farrowing induction did not influence (P > 0.10) colostrum yield (3.96 ± 0.20 kg) or piglet BW gain during d 1 postpartum (116 ± 8 g). At the onset of farrowing (T0), lactose content in colostrum was greater in IF sows than in NF sows (P < 0.05), whereas colostrum ash and protein contents were less (P < 0.05) in IF sows. Concentrations of IgG in colostrum were similar in both groups of sows, whereas concentrations of IgA at T0 were less in IF than in NF sows (P < 0.01). Overall, endocrine changes in blood from d -2 until d 2 (cortisol, prolactin, progesterone, and estradiol-17β) were not altered by farrowing induction (P > 0.10), but 1 h after the injection of alfaprostol, IF sows had greater circulating concentrations of prolactin (P < 0.01) and cortisol (P < 0.10) than NF sows. The greater concentration of lactose in colostrum from IF sows could be attributed to this transient increase in prolactin and cortisol. At birth, concentrations of white blood cells were less in piglets born from IF sows (P < 0.01). On d 1 and 21, piglets from IF sows had similar IgG concentrations in plasma to piglets from NF sows (P > 0.1). In conclusion, farrowing induction at 113 d of pregnancy induced transient hormonal changes in sows and alterations in colostrum composition, without significantly affecting colostrum yield. It also modified some hematological variables of piglets at birth.

Widespread divergence between incipient Anopheles gambiae species revealed by whole genome sequences

The Afrotropical mosquito Anopheles gambiae sensu stricto, a major vector of malaria, is currently undergoing speciation into the M and S molecular forms. These forms have diverged in larval ecology and reproductive behavior through unknown genetic mechanisms, despite considerable levels of hybridization. Previous genome-wide scans using gene-based microarrays uncovered divergence between M and S that was largely confined to gene-poor pericentromeric regions, prompting a speciation-with-ongoing-gene-flow model that implicated only about 3% of the genome near centromeres in the speciation process. Here, based on the complete M and S genome sequences, we report widespread and heterogeneous genomic divergence inconsistent with appreciable levels of interform gene flow, suggesting a more advanced speciation process and greater challenges to identify genes critical to initiating that process.

Impact of an extended photoperiod in farrowing houses on the performance and behaviour of sows and their litters

The effects of an extended photoperiod around parturition and throughout lactation on performances of primiparous sows and their piglets were studied. Sows were assigned to two light regimens: (1) standard (CTL, n = 28), 8 h of daily light from day 112 of gestation until day 23 of lactation; and (2) extended (TRT, n = 26), 23 h of daily light from day 112 of gestation to day 4 of lactation and 16 h thereafter. Colostrum intake was estimated based on a 24-h piglet weight gain starting at the end of farrowing. Piglets were weighed on days 4, 7, 14, 21 (weaning on day 23), 35 and 56. On days 4 and 21 of lactation, milk and blood samples were obtained. Behaviour was recorded on days 3 and 20. Piglet feed intakes were noted post-weaning until day 56. The TRT sows had lower concentrations of melatonin than the CTL sows on day 4 (P < 0.05), but prolactin concentrations, milk composition and colostrum intake by piglets were unaffected by treatment (P > 0.1). Litter growth during lactation was unaffected (P > 0.1), but TRT piglets consumed less feed between 23 and 34 d of age (P < 0.05) and weighed less on day 35 (P < 0.05). The TRT piglets were more active than CTL piglets on day 3 of lactation only (P < 0.05). Increasing the period of daily light in the farrowing house did not improve the performance of primiparous sows and their piglets. Key words: Behaviour, growth, lactation, photoperiod, piglet, sow

Greater milk yield is related to increased DNA and RNA content but not to mRNA abundance of selected genes in sow mammary tissue

The relationship between greater sow milk yield and mammary development, expression of selected genes in mammary tissue and hormonal concentrations in lactating sows was studied. Crossbred sows were separated in two groups according to the weight gains of their piglets up to day 21. The groups were: (1) lower milk yield (LOW, n = 14) and (2) higher milk yield (HI, n = 14), representing lactation weight gains of 4.46 and 5.25 kg pig-1, respectively. Jugular blood samples were obtained from all sows on day 3 (for prolactin determination) and day 23 (for measures of prolactin, leptin, insulin, glucose and free fatty acids) of lactation, and milk samples were collected on days 3 and 22. At weaning (day 23), sows were slaughtered and their mammary glands were collected, dissected and composition was determined. Mammary parenchymal tissue was analyzed for the mRNA abundance of selected genes. Hormone concentrations in blood did not differ between groups (P > 0.1) and on day 3 of lactation, dry matter and leptin contents in milk were lower (P < 0.05) in HI than in LOW sows. There was more DNA and RNA per teat in HI than LOW sows (P < 0.05), whereas the expression of selected genes within mammary tissue was unaffected (P > 0.1) by production group. Significant correlations (P < 0.01) existed between average weight gain of piglets during lactation and mammary RNA and DNA, expressed either as total amount or amount per teat, at weaning. Sow milk yield is therefore related to mammary gland composition in late lactation.Key words: Genes, lactation, mammary gland, milk yield, sow

Altrenogest treatment during late pregnancy did not reduce colostrum yield in primiparous sows

The decrease in circulating concentrations of progesterone is the lactogenic trigger in many species. The aim of the present study was to determine the effect of an orally active progestogen, altrenogest, administered in late gestation, on lactogenesis in sows. Gilts were treated with altrenogest (20 mg/d) from d 109 to 112 of gestation (ALT112, n = 6) or d 113 (ALT113, n = 8) or were not treated (control, n = 9). Colostrum production, estimated from the BW gains of the piglets, was measured during 24 h starting at the onset of parturition. Colostrum samples were collected at the onset of parturition until 48 h later. Jugular blood samples were taken from d -8 prepartum until d 3 postpartum. Altrenogest treatment extended the gestation length of ALT113 sows in comparison with control sows (116.3 vs. 114.7 d; P < 0.05). Litter size and litter weight at birth did not differ between groups (P > 0.1). Estimated colostrum yield was not reduced in altrenogest-treated sows compared with control sows (4.20 kg) and tended to be greater in ALT112 (4.73 kg) than in ALT113 sows (3.74 kg; P = 0.09). Altrenogest reduced endogenous progesterone concentrations during the 2 d prepartum in ALT113 relative to control sows (P < 0.05), likely because luteolysis occurred earlier in relation to parturition in ALT113 sows. Altrenogest reduced estradiol-17beta concentrations during the 2 d prepartum in ALT113 (P < 0.05) and ALT112 (P < 0.1) sows. Altrenogest treatment did not influence the timing of the prepartum peak of prolactin in relation to parturition. The ALT113 sows had lesser (P < 0.05) concentrations of lactose in plasma and a lesser Na:K ratio in colostrum after parturition than Control and ALT112 sows, indicating that the junctions between their mammary epithelial cells were tighter. Concentrations of colostral IgG in sows that received altrenogest tended to be less than in control sows (P = 0.08). In conclusion, altrenogest administered from d 109 to 112 or 113 of pregnancy did not affect lactogenesis in sows, possibly because the treatment delayed farrowing and main hormonal changes without affecting the relative chronology of these changes.

Carcass Composition and Resistance to Fasting in Neonatal Piglets Born of Sows Immunized against Somatostatin and/or Receiving Growth Hormone-Releasing Factor Injections during Gestation

Thirty-eight gestating sows were either immunized against somatostatin (SRIF) and/or injected with growth hormone-releasing factor (GRF). Treatment effects on carcass composition and resistance of newborn piglets to a 60-hour fast were investigated. Protein content of carcasses at birth was increased in piglets of sows receiving GRF or immunized against SRIF, however, when sows received both treatments there was a reduction in carcass protein content (p = 0.01). Other carcass components were unaltered by treatments, and none of the treatments affected metabolic or endocrine profiles of piglets at birth. Concentrations of GH, IGF-I (p less than 0.01), glucagon and cortisol (p less than 0.05) increased linearly with duration of fast, whereas glucose values decreased. Resistance to fasting was unaltered in piglets from any treatment thereby suggesting that exogenous GRF and/or SRIF immunization of sows during gestation are unlikely to improve survival of newborn piglets.

Effect of age on the behavioral and physiological responses of piglets to tail docking and ear notching

Neonatal piglets are often subject to potentially painful processing procedures such as tail docking and ear notching during the first few days after birth. However, these procedures may influence the development of suckling behavior and passive transfer of immunoglobulins, especially if done within the first day postpartum. The objective of this experiment was to compare the effects of processing piglets during the first 24 h versus at 3 d of age on suckling and pain-related behavior, the passive transfer of immunoglobulins, and growth. Six piglets per litter from 20 litters (n = 120 piglets) were used in a 3 x 2 complete block design. Piglets were weighed at birth and assigned to 1 of 3 treatments (balanced by birth weight): control (unmanipulated), sham processed (manually manipulated), and processed (tail docked and ear notched) at 1 of 2 ages (1 or 3 d of age). Vocalizations were recorded during the procedures, and piglets were observed after the procedures for pain-related behavior. Suckling behavior was observed for 6 h on each of d 1 to 4. Colostrum samples were collected after the birth of all piglets (before first suck), and blood samples were collected on d 5 to examine concentrations of immunoglobulins (IgA and IgG) and IGF-I. Body weights were measured at birth and on d 5 and 14. During the procedures, processed piglets, regardless of age, vocalized at a greater frequency (P < 0.001) and produced more high frequency calls (P = 0.016) than sham-processed piglets. All piglets on d 1 produced more high frequency calls than all piglets on d 3 (P = 0.047). Immediately after the procedures, sham-processed and processed piglets spent less time lying and more time standing than control piglets (P < 0.001), whereas processed piglets jammed their tail between their legs more than sham-processed or control piglets (P < 0.001). Lying, standing and tail posture were not influenced by age, nor were there age by treatment interactions. Piglets on d 1 trembled more than piglets on d 3 (P < 0.001), and this tended to be exacerbated by processing (P = 0.076). There was no effect of treatment or age of treatment on suckling behavior. Processed piglets had decreased IgG serum concentrations compared with sham-processed and control piglets (P = 0.029), although there was no interaction between treatment and age of treatment (P = 0.67). Whereas tail docking and ear notching do appear to result in short-term pain and modulated immune status, processing on d 1 appears neither better nor worse than processing on d 3.

Feeding flaxseed to sows during late-gestation and lactation affects mammary development but not mammary expression of selected genes in their offspring

Mammary gland composition and mammary gene expression were measured in pubertal gilts whose dam were fed a control (CTL) diet or a diet with a 10% supplement of flaxseed (FS) during late-gestation and throughout lactation. Parenchymal weight expressed as a percentage of body weight tended to be greater in offspring from FS compared with CTL sows (P < 0.1) and to contain less fat (P < 0.1). Offspring from FS sows had more parenchymal protein, whether expressed as a percentage (P < 0.05) or total amount in tissue (P ≤ 0.05), than offspring from CTL sows. No changes (P > 0.1) in mammary gland expression of the studied genes were observed with dietary treatment. Key words: Flaxseed, gene expression, gestation, mammary development, offspring, porcine

Nutritional, hormonal, and environmental effects on colostrum in sows

It is widely recognized that an early and high intake of colostrum is a major determinant of piglet survival during the early suckling period. The production of colostrum, however, is very variable among sows and the factors affecting this variability are not well known. Factors such as number of parity and genotype do seem to influence colostrum yield and composition. The endocrine status of the sow also affects the process of colostrogenesis and changes in the sow endocrine status can have an impact on quantity and quality of colostrum produced. Indeed, induction of parturition seems to play a role. Nutrition is undoubtedly a major factor that could be used as a tool to alter colostrum composition, with fat content being the most affected. Feed ingredients, such as yeast extracts and fermented liquid feed, were recently shown to alter colostrum composition, yet more research is needed to substantiate these effects. Very few data are available on the influence of environment on colostrum production; results suggest that heat stress has negative effects on colostrum composition. Considering the importance of colostrum for the survival, growth, and immune resistance of piglets, it is obvious that research on the development of new management systems is necessary to improve yield and composition of colostrum.

Review: Current knowledge on mammary blood flow, mammary uptake of energetic precursors and their effects on sow milk yield

Dietary availability of nutrients to the mammary gland is a major limiting factor for sow milking potential. Nutrient availability to the udder is estimated by measuring mammary arteriovenous differences, which are affected by blood flow as well as circulating concentrations of nutrients. Mammary blood flow can be measured either directly or indirectly. Even though it is influenced by numerous factors, such as time since feeding, postural behavior, vasoactive substances, ambient temperature and litter size, authors report that the amount of plasma required to produce 1 kg of milk for a litter of 12 pigs ranges from 490 to 1050 L at peak lactation. Blood glucose is the major precursor for lactose synthesis and reported extraction rates of glucose by the mammary gland vary between 20 and 31%. Other metabolic precursors, such as triglycerides, phospholipids, acetate, propionate and lactate are also used for milk synthesis. There exists a discrepancy between estimates of energetic efficiency depending on the type of study conducted (metabolism vs. mammary balance). Endocrine status of the sow may affect mammary nutrient availability. There still exists a gap in our knowledge on relative mammary uptakes of energetic compounds other than glucose and on glucose transporter systems in porcine mammary tissue. The need for such information is of particular importance due to the increased milking demands currently made on lactating sows. Key words: Blood flow, lactation, mammary gland, nutrient uptake, sows

Influence of genotype on metabolic variables, colostrum and milk composition of primiparous sows

Composition of colostrum and milk in first-parity sows from four genetic lines, namely, synthetic Belgian Landrace/Pietrain (B), Duroc (D), Landrace (L) and Yorkshire (Y) were determined. Circulating concentrations of leptin, IGF-I, glucose and FFA were also measured in sows. Differences in colostrum and milk composition were observed between genotypes, but did not generally seem related to variables in blood. Colostrum and day-2 milk from D sows contained more protein (P < 0.05) and less lactose (P < 0.1) than that from sows of other genotypes. Results suggest that selection strategies to improve the composition of milk and colostrum of sows from European breeds could be a useful tool to increase their lactation potential. Key words: Colostrum, lactation, milk composition, sow

Effects of dietary supplementation with flax during prepuberty on fatty acid profile, mammogenesis, and bone resorption in gilts1,2

The possible role of dietary flax on pre-pubertal development of mammary glands and bone resorption was investigated in gilts. Fifty-seven gilts were fed 1 of 4 diets from 88 d of age until slaughter (d 212 +/- 1). Diets were control without flax (n = 14); 10% flaxseed supplementation (n = 13); 6.5% flaxseed meal supplementation (n = 15); and 3.5% flaxseed oil supplementation (n = 15). All diets were isonitrogenous and isocaloric. Jugular blood samples were obtained on d 78 and 210 to establish the fatty acid profile and to determine the concentrations of prolactin, estradiol, and cross-linked N-telopeptides of type I collagen. At slaughter, the mammary glands were excised, parenchymal and extraparenchymal tissues were dissected, and the composition of the parenchymal tissue (protein, fat, DM, and DNA) was determined. Histochemical analyses of the mammary parenchyma were performed, and fatty acid profiles in the extraparenchymal tissue were evaluated. Dietary flax increased (P < or = 0.001) the concentrations of PUFA and decreased those of SFA (P < 0.01) and MUFA (P < or = 0.001) in plasma and extraparenchymal tissues, which was largely due to the inclusion of 10% flaxseed or 3.5% flaxseed oil (P < or = 0.01) but not 6.5% flaxseed meal. Circulating concentrations of prolactin and estradiol were unaltered by treatments (P > 0.1), but concentrations of cross-linked N-telopeptides of type I collagen tended to be greater (P < 0.1) in flax-supplemented gilts. The DM content of parenchymal tissue was the only mammary compositional value affected, showing an increase with flax addition (P < 0.05). No change (P > or = 0.1) in the bromodeoxyuridine labeling index or estrogen receptor localization was observed with treatments. Dietary supplementation with flax as seed, meal, or oil, therefore, brought about the expected changes in the fatty acid profile but had no beneficial effects on mammary development or bone resorption.

Mammary gland involution and endocrine status in sows: Effects of weaning age and lactation heat stress

The effects of lactation length and/or heat stress on endocrine status of sows and indicators of mammary involution at weaning were studied. Twenty-eight first parity Yorkshire × Landrace sows were housed at 21 (CTL) or 29°C (HS) throughout lactation. Within each temperature group, half the sows were randomly assigned to a weaning age of 22 (W22: CTL, n = 7; HS, n = 8) or 44 d (W44: CTL, n = 6; HS, n = 7). Litter size was standardized to 10 or 11 on day 2 and to 9 on day 23 of lactation. Blood and milk samples were collected on days -1, 1, 2 and 3 relative to weaning (day 0). Concentrations of prolactin, IGF-I and lactose were measured in both fluids and concentrations of Na, K and IGFBP-5 were measured in milk. Standard milk composition was also determined. Lactose was lower (P < 0.001) and protein greater (P < 0.05) in all milk samples from W44 compared with W22 sows. Percentages of milk fat and dry matter were lower (P < 0.05) in W44 than in W22 on days 2 and 3 post-weaning. Milk lactose was reduced (P < 0.05) with heat stress on days 2 and 3. The day before weaning, concentrations of prolactin in blood (P < 0.001) and lactoserum (P < 0.01) were lower and those of IGF-I in lactoserum were greater (P = 0.01) in W44 than in W22. Values of IGFBP-5 in milk were drastically lower (P < 0.001, more than a fourfold difference), those of Na greater (P < 0.001) and those of K unchanged (P > 0.1) for W44 compared with W22. Post-weaning, evidence of leaky tight junctions (increased milk Na, decreased K) was evident a day earlier (2 vs. 3) in W44 compared with W22 and was most marked in HS. In support, plasma lactose concentrations increased transiently on the same day in HS W44. The greater Na/K ratio in W44 compared with W22 taken together with increased plasma lactose particularly in HS shows that mammary epithelial cell tight junctions become leaky as lactation advances. Weaning age therefore has an impact on milk variables which are indicative of the status of mammary involution in sows and some of these effects are exacerbated by heat stress. Key words: Heat stress, lactation length, mammary involution, sows, weaning