Effects Of Litter Size Research Articles

PSV-10 Free-choice diet selection by sheep during peripartum

Abstract Our objective was to explore diet selection and productive performance by sheep during peripartum. Pregnant Saint-Croix and Katahdin ewes were housed in individual pens from 100 days of gestation to 60 days of lactation and assigned to two groups: Free-choice-FC and Mixed-ration-MR (n = 12/group). Sheep in FC received ad-libitum amounts of soybean meal, sorghum grain, alfalfa and oat hays, presented in individual troughs. Animals in MR received a total-mixed-ration with these feeds, balanced for gestation or lactation according to NRC. Dry matter (and nutrient) intake/kg BW was measured daily, whereas BW and BCS were measured every 7 and 14 d, respectively. Data was analyzed as a Linear Mixed Model with repeated measures; group, breed, litter size (single, twins) and parity (primiparous, multiparous) were the fixed factors and sheep (random factor) was nested within group. Overall dry matter and ME intake did not differ between groups (P > 0.05), without breed, litter size or parity effects (P > 0.05), but protein intake was greater and NDF and ADF intakes were lower in FC than in MR (P < 0.001). During gestation, FC sheep consumed soy=alfalfa >sorghum >oats, and during lactation they increased (2X) soy intake (P < 0.001). Body weight was similar between groups (73.3±1.3, and 70.6±1.3 kg, for FC and MR, respectively; P=0.148), whereas BCS was greater for FC than for MR (3.9±0.2 vs. 3.3 ±0.1; P = 0.01). During lactation, ewe BW (67.3±1.3 vs. 61.92±1.3 kg; P = 0.01) and BCS (3.83±0.1 vs. 3.03±0.1; P < 0.001) were greater for FC than for MR. Offspring BW was similar between groups (11.5±0.6, and 11.4±0.5 kg, for FC and MR, respectively; P = 0.804). In conclusion, the free-choice treatment enhanced ewe nutrition, reducing BW and BCS losses during lactation without influencing offspring growth. Free-choice may enable ewes to meet their individual nutrient needs, with benefits to their welfare and postpartum ovarian activity.

Associations between litter size and medical treatment of sows during farrowing and lactation

ABSTRACT Sow litter sizes have increased recently, and there is a lack of data on the effect of litter size on sow health and sow medical treatment. This study investigated associations between litter size and medical treatment of sows, using data for a 10-year period from one Swedish research farm. The data comprised 1947 litters from 655 Yorkshire sows. Association between litter size and medical treatment of sows during farrowing and lactation investigated using a multivariable multilevel logistic regression model. We found that odds of medical treatment of sows decreased for each additional piglet born up to five piglets (odds ratio 0.50, p = .002). For litter sizes ≥5, the odds for each additional piglet born (odds ratio 1.11, p < .001). Problems with milk let-down in early lactation were the main reason for treatment. Results imply that sows with very small or very large litters may be less profitable.

Differential Responses of Liver and Hypothalamus to the Nutritional Condition During Lactation and Adult Life.

It was previously reported that liver glucose metabolism in rats under caloric restriction differs from that of freely-fed rats. This study hypothesized that these changes (1) were related to the expression of hypothalamic neuropeptides involved in metabolic control, and (2) were not a residual effect of litter size. To those purposes, liver glucose metabolism and hypothalamic expression of the orexigenic neuropeptides NPY (neuropeptide Y) and AgRP (agouti gene-related peptide); and of the anorexigenic neuropeptides POMC (pro-opiomelanocortin) and CART (cocaine- and amphetamine-related transcripts) were investigated. Male Wistar rats from two different litter sizes (G6 and G12, with 6 or 12 pups, respectively) were subjected to free feeding (GL, ad libitum), 50% caloric restriction (GR) or caloric restriction+ad libitum refeeding (GRL) until the age of 90 days. Biometric values were lower in GR than in GL, while in GRL they were totally or partially recovered. Blood glucose variation during the pyruvate tolerance test (PTT) was small in GR. During in situ liver perfusion, total, basal, and adrenaline-stimulated liver glucose outputs were high in GR, but additional glucose output in the presence of alanine was negligible. Refeeding (GRL) yielded values close to those of GL. Litter size did not consistently influence any of these variables. The expression of transcripts of the hypothalamic neuropeptides was responsive to feeding regimen, litter size and/or their interaction and differed from G6 to G12, while the metabolic changes of the liver were qualitatively equal in both GR. Therefore, the changes in glucose metabolism in the liver of rats under caloric restriction were not determined by either litter size or hypothalamic neuropeptide expression and were linked only to the prevailing feeding regimen of the adult animal.

Effect of large litter size and within-litter differences in piglet weight on the use of milk replacer in litters from hyper-prolific sows under two housing conditions

Due to genetic selection for large litters in pig production, piglets are often supernumerary to the teats on the sow. Providing milk replacer as a second feed source is increasingly being used to rear large litters. This results in increased competition at the udder when all piglets remain at the sow. We hypothesise that larger litter size and being amongst the smaller piglets within-litter (irrespective of absolute weight) is associated with increased likelihood of drinking milk replacer as a supplement to suckling or to compensate for low suckling success. The study design was 2 × 2 factorial with two standardised litter sizes at day 1 (LSD1) of either 14 piglets (LS14) or 17 piglets (LS17) and two housing conditions in either crates (CRATE) or loose housing (LOOSE). If piglets died, they were not replaced. The piglets’ suckling and drinking behaviour along with their growth rate was recorded weekly. The results showed a clear preference for suckling the sow over milk replacer. None of the piglets changed entirely to drink milk replacer. LS17 compared to LS14 was associated with more piglets with low suckling success (P ≤ 0.05) and the risk of having low suckling success was higher for the smaller piglets within-litter (P ≤ 0.05). About half of the piglets with low suckling success were able to compensate and sustain growth by drinking milk replacer (P ≤ 0.05). The largest piglets within-litter were more likely to drink milk replacer as supplement to high suckling success compared to only suckling (P ≤ 0.05). When taking into account the absolute weight of the piglets in the start of the week, piglets drinking milk replacer in addition to suckling had a higher growth rate in the following week compared to piglets who did not supplement suckling with milk replacer (P ≤ 0.05). Thus, the present study could confirm that some of the piglets experiencing a competitive disadvantage at the udder could compensate with milk replacer. However, the milk replacer was mainly used by the larger piglets within-litter and as a supplement to increase growth of piglets who had access to a teat. Several factors may have affected the piglets’ ability to use the milk replacer: high effort to drink from the milk cup due to inadequate design, poorer nutrient quality of milk replacer than of sow milk, and/or suckling the sow satisfies other behavioural and physiological needs than solely nourishment.

Milk lactoferrin concentration of primiparous and multiparous sows during lactation

Lactoferrin (LF), a sialylated iron-binding glycoprotein, has numerous vital physiological functions including immunomodulation and protection against a large group of microorganisms, improving neurodevelopment, health, growth performance, and milk production. Lactoferrin occurs in human milk at a higher concentration compared with bovine milk, but little information is available on LF concentrations in porcine milk and the effects of sow parity on milk LF concentration. The objective of this study was to quantify the LF concentration in porcine milk and to compare that concentration between gilts and sows during lactation. We also investigated the effect of genetic background and litter size of the female pig on the LF concentration of porcine milk. The milk from 30 gilts and 35 sows was collected at 3 stages of lactation, namely colostrum, transition, and mature milk. Standard and experimental samples were analyzed by ultra-high performance liquid chromatography using a diode array UV detector. The following findings were reported: (1) porcine milk contained significant levels of LF with the highest concentration in colostrum, which decreased by ∼62% and ∼67% in transitional and mature milk, respectively; (2) mature gilt milk contained a 22% higher concentration of LF compared with sow milk, which was statistically significant; (3) breed line had an overall significant effect on the LF content of porcine milk; however, when the breed was considered, no significant difference was observed; and (4) LF concentration of porcine milk was not significantly influenced by the litter size. The presence of LF in a higher concentration in porcine milk suggests that LF is an important constituent of pig milk that might contribute to the optimum growth and development of piglets.

Differential Effects of Litter Size and Within-Litter Birthweight on Postnatal Traits of Fatty Pigs.

Simple SummaryThe current work evaluated the relative effects of the number of piglets in the litter of origin (high vs. low litter size) and the birthweight (low (LBW) vs. normal (NBW) in large litters) on postnatal performance and quality of carcasses and meat in purebred Iberian pigs. The results indicated that NBW piglets born in large litters had disparities in developmental patterns in weight and size, back-fat deposition, and fatty acid composition of viscerae compared to NBW piglets from small litters, which again were different from those found in LBW piglets when compared to their NBW counterparts. However, both growth patterns were altered and might indicate previous phases of metabolic disorders.Fatty pigs are characterized by a thrifty genotype, adapted to harsh environments based on changes in metabolism and energy saving. Thus, we hypothesized that feto-maternal energy partitioning in large litters might have postnatal effects that might be independent of intrauterine growth restriction (IUGR) processes. Hence, the current work reported the influence of two effects on postnatal performance and carcass and meat quality of purebred Iberian pigs: (a) the effects of the number of piglets in the litter (high vs. low litter size), and (b) the effects of birthweight (low (LBW) vs. normal (NBW)) in large litters. The results confirmed that NBW piglets born in large litters had differences in developmental patterns of weight, back-fat deposition, and fatty acid (FA) composition when compared to NBW piglets from small litters. These results were different from those found in LBW piglets when compared to their NBW counterparts, which showed an initial asymmetrical growth and altered muscle FA composition at slaughtering. The assessment of FA composition indicated better metabolic status in NBW piglets from large litters than in LBW piglets. These data support the concept that the prenatal environment, even when the individual may cope with it, inescapably affects postnatal life.

Effect of litter size, milk replacer and housing on behaviour and welfare related to sibling competition in litters from hyper-prolific sows

Litter sizes where piglets are supernumerary to teats leads to the practice of fostering to nurse sows or to artificial rearing systems, which is associated with compromised welfare. An alternative strategy is to leave the supernumerary piglets with their own dam and provide milk replacer in the farrowing pen. To provide sufficient space around the sow’s udder, loose housing could be an alternative to the use of farrowing crates. However, large litters have been associated with increased teat fighting, abrasions on sows and piglets and signs of hunger. The aim of this study was to investigate whether provision of milk replacer and/or loose housing could alleviate signs of hunger and sibling competition at the udder. Ninety-eight litters were studied in a 2 × 2 factorial design. The sows were housed in crates or loose (CRATE/LOOSE), and litters had access to milk replacer or no milk replacer (+MILK/-MILK). The litter size was either 14 or 17 piglets on day 1 postpartum but decreased as piglets died. Recordings included drinking bouts of milk replacer, teat fighting, udder massage and abrasions on sow and piglets. On day 3, at least one observation of milk replacer consumption was observed in 90% of the litters in +MILK but at less than five bouts per litter/12 h in all except two litters. On days 7, 14 and 21, 59-65% of the piglets in +MILK consumed milk replacer at least once with a mean frequency of 0.4-1.9 bouts/h/piglet. Increasing litter size resulted in more piglets involved in teat fighting, having low suckling success and snout abrasions (P < 0.05). The risk for all indicators were generally higher for smaller compared to larger piglets. Access to milk replacer reduced risk of piglet snout abrasions (P < 0.05), but not of teat fighting (P> 0.1). Loose housing reduced the risk of udder abrasions (P < 0.05) and tended to decrease udder massage (P < 0.10). Thus, milk replacer and loose housing minimally reduced litter competition in litters from hyper-prolific sows, indicating that supplementing large litters with milk replacer can be associated with compromised welfare. The welfare consequences of using milk replacer appear comparable to when surplus piglets are fostered by nurse sows or artificially reared. Before supplementing milk replacer to large litters is further applied under commercial conditions, research and innovation is needed to improve quality of milk replacer and cup design to alleviate the negative impact on welfare.

Effect of litter size, kidding age, mating weight, and kidding weight on partial cumulative milk yields in G1 Sapera goat

Milk Production of the dairy goat is influenced by genetic and non-genetic factors. Crossbred dairy goat of Sapera (50% Saanen, 50% PE) has been formed by the Indonesian Research Institute for Animal Production (IRIAP). Genetic improvement of milk production is the main trait considered in forming Sapera goat, so the effects of non-genetic factors on milk production should be investigated. Effects of litter size, kidding age, mating weight and kidding weight were examined on weekly cumulative milk yields (week 1-14) in Generation 1 (G1) Sapera goat (28 heads) at RIAP. General Linear Model for unbalanced data was used to study the effects of those four factors, while mean differences among subfactors were tested by the Duncan test. The G1 Sapera does had kidding age, litter size, mating weight, and kidding weight successively 4.22±1.45 yrs old, 2.07±0.55, 49.0±11.43 kg, and 44.4±11.75 kg. Higher litter sizes resulted in more milk yields, but litter size effects decreased by the lengthening lactation. Kidding age at ≥ 5 yrs old produced higher milk yields than the younger does (3 and 4 years old). The mating weight did not affect milk yields, while does having kidding weigh ≥ 70 kg resulted from lower milk than other weights. Considerable variation for various partial cumulative milk yields among G1 Sapera does have a good indication for possible selection on milk production in Sapera dairy goat.

Litter size and cub age influence weight gain and development in American black bears (Ursus americanus)

AbstractWe assessed the effects of cub age, litter size, and sex, on body mass (BM), absolute and relative growth rates (AGR, RGR), opening of ears and eyes, and deciduous teeth eruption from 129 cubs of American black bears (Ursus americanus) born at Virginia Tech’s Black Bear Research Center. Specific ages, related to maternal food consumption, and litter size, best described BM, AGR, RGR, and ear and eye development. Overall, newborns weighed ~0.44 kg at birth and increased ~9-fold by ~14 weeks. Twins were greater in BM than single cubs and triplets. Single and triplet cubs had higher AGR and RGR than twins after mothers resumed food consumption post-hibernation. Newborns displayed RGR &amp;gt; 3.5% that decreased until den emergence (RGR &amp;lt; 3.5% after emergence). RGR differed among litter sizes, particularly after den emergence. Ear and eye opening occurred concurrently at ~44 days of age, while teeth erupted ~10 days later. Single cubs experienced delayed development of these organs compared to other litter sizes. Postnatal developmental differences between black bears and other carnivores likely stem from strategies allowing black bears to minimize energy expenditure during the gestational period when hibernating.

KAJIAN PERFORMA BOBOT PRASAPIH DOMBA GARUT DI UPTD-BPPTDK MARGAWATI GARUT (Study on the Performance of Preweaning Weight of Garut Sheep at UPTD-BPPTDK Margawati Garut)

The development of local genetic resources is important to meet the need of high demand of lamb meat in Indonesia, especially in West Java, through the selection of superior breeds of Garut sheep. The selection has to be initiated by studying the Garut sheep performances to determine the environmental factors affecting the preweaning performances of the sheep and involving those factors in the analysis of genetic parameters. The study was held on the Unit Pelayanan Teknis Dasar Balai Pengembangan Perbibitan Ternak Domba dan Kambing (UPTD-BPPTDK) Margawati Garut from August 21st to September 18th, 2019. The purpose of this experiment was to study the effect of sex and litter size on preweaning weight, i.e birth weight, weight on 30, 60, 90 days, and weaning weight (100 days). The traits were analyzed on 6.349 heads, 3.214 rams, and 3.135 ewes, from 2012 to 2019 using the General Linear Model (GLM) and Duncan multiple range test of SAS 9.0 software. The fixed effects used in the analysis were the sex and the birth type. The results showed that the performance of Garut Sheep based on the preweaning weight was affected significantly (P&lt;0.05) by the sex, with the average of birth weight, 30, 60, 90 days weight and weaning weight (100 days) were 2.46 kg, 5.64 kg, 7.73 kg, 9.92 kg, 10.97 kg (rams) and 2.33 kg, 5.42 kg, 7.34 kg, 9.36 kg, and 10.28 kg (ewes). The pre-weaning weight was also significantly affected (P&lt;0.05) by the birth type, in which the average of birth weight, 30, 60, 90 days weight and weaning weight (100 days) were 2.96 kg, 6.49 kg, 8.98 kg, 11.29 kg, 12.52 kg (single), 2.25 kg, 5.09 kg, 6.78 kg, 8.71 kg, 9.52 kg (twin), 1.79 kg, 4.62 kg, 6.24 kg, 8.09 kg, 8.92 kg (triplet), 1.54 kg, 4.53 kg, 5.89 kg, 7.15 kg, 8.03 kg (quadruplet), and 1.51 kg, 3.84 kg, 5.23 kg, 6.58 kg, 7.15 kg (quintuplet). Based on the results, preweaning weight must be corrected by the sex and the birth type before the genetic parameters are analyzed to avoid bias of selection results.

Hycole Doe Milk Properties and Kit Growth.

Simple SummaryThe rabbits used on the commercial rabbit farms for the production of rabbit fryers are crosses of synthetic lines, such as Hycole. The maternal rabbit lines are selected not only for high number of kits but also for high production of milk. The goal of the presented study is related to the lack of complex data on the quality of rabbit milk, though this milk determines the nutritional status of kits in the suckling period as well as body weight gains and survival of rabbit kits. There are data on the milk yield of rabbit does and the milk proximal chemical composition, but the hygienic quality of this milk (somatic cell count) and its relationship with milk yield, kits survival, and weight gains is an unanswered question. The presented findings show the significant relationship between litter size, which has a clear effect on the milk production, as well as litter weight. Also shown is that the day of lactation affected the physiochemical traits of rabbit milk.The level of production and the physiochemical traits of rabbit milk affect the growth and the mortality of bunnies during lactation. The goal of the study was to analyze the effect of litter size and day of lactation on the quality traits of rabbit milk, milk production, and associative traits. The study was conducted on 32 Hycole does and their litters. The rabbit milk pH ranged from 6.61 to 7.46. The colostrum was characterized by the highest content of total solids (31.54 and 31.80 g kg−1) and fat content (15.73 and 15.9 g kg−1). The milk from the beginning of the lactation was characterized by the highest level of somatic cell count (SCC) (523.67 and 536.57 103 mL−1), which gradually decreased to reach the lowest level on days 17 and 21 of lactation. The daily milk production was greater for does nursing 10 kits per litter compared to those nursing eight kits per litter (p < 0.001). The peak of milk production occurred on day 17 postpartum. To conclude, the litter size has a clear effect on milk production as well as litter weight and litter weight gains. It is also important to note that the day of lactation affected the physiochemical traits of rabbit milk.

Influence of litter size at birth and weaning on the proportion of Pelibuey ewes treated with an anthelmintic in a targeted selective scheme in the hot humid tropics

Abstract The present study described the effect of litter size at birth and weaning on the frequency of AH treatments of Pelibuey ewes in a targeted selective treatment (TST) scheme under hot humid tropical conditions. It also compared the time (days) elapsed from parturition to the moment when 50 % of ewes in each litter size category received an AH treatment. A prospective observational study was performed during six months of the rainy season (June to December 2016). Ninety-one pregnant Pelibuey ewes were gradually included in the study from lambing day until 75 days postpartum. Litter size and lambs’ weight at birth and weaning were recorded for each dam, as well as lamb mortality. At parturition and every 15 days each dam’s body condition score (BCS), hematocrit (HT) and faecal egg counts (FEC) of GIN was recorded. On those same dates, ewes with BCS 1000 eggs per gram of faeces (EPG) were treated with an AH (Levamisol 12 %, 7.5 mg/kg BW), and those treatment events were recorded. Contingency tables were used to analyze the association between the frequency of treatments and litter size at birth or weaning. Respective Kaplan-Meyer tests compared the time (days) elapsed from parturition to the day when 50 % of the ewes were treated with AH in different litter size categories. General linear models evaluated the effect of AH treatment on lambs’ weights at weaning. Ewes lambing triplets showed a higher risk of receiving AH treatment than ewes lambing singles (P

Effect of litter size, milk replacer and housing on production results of hyper-prolific sows

The modern hyper-prolific sow gives birth to more piglets than she has functional teats (in the following called supernumerary piglets). The aim of the present study was (1) to investigate the production consequences of hyper-prolific sows rearing supernumerary piglets equal to the mean live-born litter size, and (2) investigate whether potential negative effects on survival and growth could be alleviated by providing access to milk replacer and/or providing easier access to the udder (by loose housing). At day 1 (D1) postpartum (pp), 93 litters were standardised to 14 or 17 piglets (LS14/LS17) after which no piglets were moved between sows leading to decreased litter size if piglets died. Litters were provided with or without milk replacer in milk cups (+MILK/−MILK), and sows were either crated or loose housed (CRATE/LOOSE) in a 2 × 2 × 2 factorial design. Piglet mortality was higher in LS17 compared to LS14 (P < 0.01; OR = 2.0), higher in −MILK compared to +MILK (P = 0.01; OR = 1.2) and higher in LOOSE compared to CRATE (P = 0.02; OR = 1.8). This study showed that sow rearing of supernumerary piglets while supplying with milk replacer can increase piglet survival. It also showed that early mortality before piglets learned to drink milk replacer posed a challenge using this automatic milk replacer system. An interaction between access to milk replacer and the standardised litter size D1 affected litter weight (P < 0.01) and piglet weight day 28 (D28) (P = 0.03). The highest litter weight D28 was found in LS17 +MILK (P < 0.01) but with a lower individual piglet weight than in LS14 −MILK. Piglet weight D28 was higher in LS14 −MILK compared to LS17 regardless of access to milk replacer. Heterogeneity in piglet weight within litters D28 was larger in LS17 (P = 0.03) but could be reduced with +MILK in CRATE (P < 0.01). No effects were found on sow weight loss and feed intake (P > 0.05). In conclusion, the results showed that sows cannot rear the supernumerary piglets without further management interventions to reduce mortality. Supplying supernumerary piglets equal to the mean live-born litter size of hyper-prolific sows with milk replacer can from results of this study be an alternative strategy to the use of nurse sows.

Piglet birthweight and sex affect growth performance and fatty acid composition in fatty pigs

This study aimed to determine the effects of piglet birthweight (BIW) and sex, and within-litter BIW variation, on postnatal growth traits and meat quality in fatty breeds of pig. In total, 406 crossbred piglets (half male, half female) born to Iberian sows were studied during their postnatal development until slaughter. After birth, piglets were classified into four BIW categories: very low, low, medium and high. There was a negative effect of low BIW on growth patterns and fatty acid (FA) composition, but effects of litter size and within-litter BIW variation were not found. The very low BIW piglets underwent a period of significant catch-up growth (P &amp;lt; 0.005) relative to high BIW piglets during the early postnatal phase, but also showed a higher feed conversion rate and lower average daily weight gain (P &amp;lt; 0.05 for both measures) throughout the study period. BIW affected development during the entire productive life, and the sex effect increased with age. As a result, the period to reach market weight was longer in very low BIW piglets, by 43 days for females and 15 days for males, compared with their high BIW counterparts. BIW and sex also influenced amount of intramuscular fat, n-3 FA content and monounsaturated FA composition. The study indicates that BIW, modulated by sex, is a critical point for productive traits in fatty pigs. These results provide a basis for future strategies to enhance productive efficiency and meat quality of traditional swine breeds.

Effect of litter size on prepartum metabolic and amino acidic profile in rabbit does

The use of modern prolific lines of rabbit does in intensive production systems leads to an increase in productivity but also causes a rise in several problems related to the does’ health status. Hence, the aim of this study was to investigate the effect of the litter size on the metabolic, inflammatory and plasma amino acid profile in rabbit does. The blood of 30 pregnant does was sampled on the 27th day of pregnancy. The does were retrospectively grouped according to the number of offspring into a high litter size group (HI, does with ≥ 12 kits; n= 16) and a low litter size group (LO, does with ≤ 11 kits; n= 14). Data were subjected to Pearson’s correlation analysis. Further, data were analysed in agreement to a completely randomized design in which the main tested effect was litter size. The linear or quadratic trends of litter size on parameters of interests were post hoccompared by using orthogonal contrasts. In addition, compared with the LO group, the HI group had lower levels of glucose (−5%; P< 0.01), zinc (−19%; P< 0.05), albumin (−6%; P< 0.05) and total cholesterol (−13%; P< 0.07), but the total bilirubin level was higher in the HI group (+14%; P< 0.05). Regarding the plasma amino acids, the HI group had lower concentrations of threonine (−15%), glycine (−16%), lysine (−16%) and tryptophan (−26%) and a higher level of glutamic acid (+43%; P< 0.05) compared with the LO group. The exclusively ketogenic amount of amino acids was lower (P< 0.06) in the HI (55.8 mg/100 ml) does compared with the LO does (56.8 mg/100 ml). These results show that a few days before delivery, rabbit does that gave birth to a higher number of offspring had a metabolic profile and an inflammatory status that was less favourable with respect to does who gave birth to a lower number of offspring. Moreover, the plasma amino acid profile points out that there was an enhanced catabolic condition in the rabbit does with a high number of gestated foetuses; it was likely related to the greater energy demand needed to support the pregnancy and an early inflammatory response.

The analysis of chinchilla (Chinchilla lanigera, M.) male reproduction. The case of a leading polish breeding farm.

Research into the chinchilla male fertility concerned mainly semen quality. Little attention has been paid to lifetime reproductive performance, essential from the economical point of view. Thus, the aim of this study was to analyze factors affecting the intensity of breeding use and lifetime performance of male chinchillas. After data transformation, the analysis of variance was performed to evaluate the effect of male birth litter size and age at the first effective mating. Additionally, the correlation coefficients for both litter sizes and litter rearing efficiency were calculated. For all traits, the linear regression on the sire's age at the first effective mating was found non-significant. Litter sizes differed slightly between seasons. The length of sire reproductive use was highly correlated (about 0.8) with the total number of litters and kits born and weaned. The total rearing efficiency was low, and in some cases negatively correlated with other traits, that is, with the total number of litters and kits born and weaned. Most sires were mated up to six dams; they were used in one polygamous set each. In total, the males sired about 60 litters each, hence the conclusion is that they could be extensively used and produce more benefits to chinchilla breeders.

Variability of piglet birth weights: A systematic review and meta-analysis.

The objective of the study was to evaluate the effects of litter size and supplementation of functional amino acids on the piglet birth weight variability through of a systematic review and meta-analysis. PubMed, ISI Web of Science, Science Direct, Scopus and SciELO are the main used databases and were searched in January 2019 by using the following keywords and their combinations: within-litter birth, weight variability, piglets, litter size, sow, amino acids, gestation, uniformity, CV and/or SD. Of the 64 pre-selected articles, only articles presenting the coefficients of variation and/or standard deviations according to the litter size and different levels of amino acid supplementation in the sow diets during gestation were selected. The average birth weights of total and live piglets were 43% lower in litters from sows with high prolificacy than those from sows with low prolificacy. The weight variability was affected by high prolificacy sows, with increases of 4.04% and 4.54% in the coefficients of variation of total and born alive piglets respectively (p=.074; p=.009). The standard deviation increased by 180g in born alive piglets to high prolificacy sows. The coefficients of variation of total and live piglets born from high prolificacy sows showed an increase of 4.04% and 4.54% respectively (p=.07; p<.05). There was a tendency for reduced weight variability with amino acids supplementation when considering the standard deviation of total born (p=.072). However, reproductive performance was not significantly influenced (p>.05). In conclusion, the average litter weight and the number of piglets born influence weight variability. Amino acids supplementation may reduce the birth weight variability between piglets. However, this effect depends on the amino acid used, the levels of supplementation and on other factors not completely addressed in this study. Thus, more research is necessary to fully elucidate this topic.

Sibling differences in litter huddle position contribute to overall variation in weaning mass in a small mammal

In altricial, litter-bearing species, huddling together with siblings during early life is a vital strategy to maintain a sufficiently high and stable body temperature. In this context, individual differences in huddling behavior within litters have been emphasized, as pups regularly occupying more central positions have relatively higher body temperatures, have quicker access to the mother’s nipples during nursing, and consequently show greater growth. However, it is not known whether such positive effects of a central litter huddle position on within-litter differences in growth translate into an overall higher weaning mass, taking into account strong contributors to among-litter growth variation, such as litter size and maternal parity. We used path analysis to investigate causal relations among these variables, based on data from 150 domestic rabbit pups from 24 litters. Our results confirmed positive, indirect effects of pups’ central litter huddle position on within-litter differences in early growth. This positive effect of a central litter huddle position also contributed to explaining a significant part of the overall across-litter variance in weaning body mass, apparent even when controlling for the direct negative effect of litter size, the direct positive effects of birth mass, and the lower offspring growth in primiparous compared to multiparous mothers. Thus, the results underline the key role of individual differences in litter huddle position in shaping within-litter but also overall variation in early growth. This might constitute an important mechanism accounting for how the positive association between body mass at birth and early growth is mediated in altricial, polytocous mammals. Huddling together with siblings during early life saves energy and thus can contribute to early growth in small, altricial mammals. However, this strategy can also lead to individual differences within the litter, as heavier pups typically occupy energetically more favorable positions in the center of the huddle. In our study, we show and compare the different causal pathways underlying this effect. Most importantly, our analysis shows that advantages in early growth arising from a more central position in the litter huddle are also apparent when comparing pups across all litters—even though there is typically a notable variation in growth among different litters, for example due to litter size and maternal (parity) effects. In conclusion, the results underline the key role of sibling interactions within the litter in shaping differences in early growth, with potential fitness consequences during later life.

The Effects of Reproductive Disorders, Parity, and Litter Size on Milk Yield of Serrana Goats.

Simple SummaryThis study aimed to evaluate the effects of reproductive disorders, parity, and litter size on a 150-day standardized milk yield of the Transmontano ecotype of the Serrana goat breed (a dual purpose breed) over a three decade period. The 150-day standardized milk yield was significantly influenced by all studied factors and their interactions. The milk yield reduction due to reproductive disorders was more intense in primiparous than multiparous goats, and in primiparous or multiparous goats of the Transmontano ecotype presenting multiple fetuses, than in those presenting singletons. This milk production pattern proves that the lactation following abortion is viable for production purposes and an improvement of production system management can play an important role in mitigating milk yield losses.Several reproductive factors may affect milk yield in goats. The main aim of this study was to evaluate the influence of reproductive disorders, parity, and litter size, and their interactions on the 150-day standardized milk yield (SMY150) of low-producing dairy goats extensively raised. A total of 148,084 lactations between 1993 and 2015 were obtained from data of the Genpro pedigree records of the Transmontano ecotype of Serrana goat breed. The presence or absence of reproductive disorders (RD) from late (>half) pregnancy (abortions followed by lactation) or at kidding, number of fetuses (single vs. multiple), and parity (primiparous vs. multiparous) of the Transmontano ecotype of Serrana goat were used as fixed effects to fit a general linear model for a SMY150 output. A significant effect (p < 0.001) of all factors on SMY150, as well as three-way interactions, were observed. The SMY150 reduction subsequent to RD was 3.7% for multiparous and 9.6% for primiparous goats carrying singletons, and 14.1% for multiparous and 18.8% primiparous goats carrying multiple fetuses. It was concluded that a new lactation following abortion occurrence is viable for production purpose in low-producing dairy goats under pastoralism. Nevertheless, the impact of RD on SMY150 varied according to the number of fetuses and the parity of the Transmontano ecotype of Serrana goats. This information should be used in decision-making practices regarding reproductive and herd health management.

Relationship between placental characteristics and puppies’ birth weight in toy and small sized dog breeds

Puppy neonatal mortality may be related to low birth weight, which has been shown in humans to be linked to placental factors. The relation between the newborn puppy and the placental characteristics has been poorly investigated in dogs. Twenty bitches, 9 toy-sized (i.e. < 5 Kg) and 11 small-sized (i.e. 5 to 10 Kg), were included in this study. During natural delivery or c-section, puppies were identified and their order of birth, sex and weight were recorded. Puppy weights were registered at birth and daily until Day 6. Placentas were weighed after removal of extraplacental adnexa, after which a photo was taken and morphometrically assessed. The Total Placental Area (TPA) and the Transfer Zone Area (TZA) were calculated and their surface expressed in mm2. Immunohistochemistry with monoclonal mouse anti CD31 antibody was used to identify fetal and maternal vessels in the placental labyrinth zone. A vascularization index (VI) was determined for each placenta and the Total Vascular Area (TVA) was estimated. Puppies' birth weight correlated positively with placental weight (P < 0.001, r = 0.689). A positive correlation was found between the puppies' birth weight and TPA (P < 0.001, r = 0.786), TZA (P < 0.001, r = 0.772), and TVA (P < 0.001, r = 0.482). A positive correlation was also found between placental weight and TPA (P < 0.001, r = 0.661), TZA (P < 0.001, r = 0.583), and TVA (P < 0.001, r = 0.333). In the small-sized breeds, the placentas of low-weight puppies were lighter and had a smaller TZA and TVA (P < 0.05). The VI was higher in the placentas of the toy-sized compared to small-sized bitches (P < 0.01). No effect of parity, litter size, or sex of the puppy was observed on birth weight or growth rates on Day 6. The growth pattern of low-weight puppies did not differ from that of the other puppies during the first 6 days of life. As in humans, placental weight, the extension of the transfer zone and placental total vascular area correlates closely with the puppies' birth weight in normal pregnancies. Our data could represent reference values for placental weight, TZA, TVA and VI in toy and small-sized dog breeds.