Dietary polymer-coated urea enhances the goats lactational performance, excretion of microbial purine derivatives and blood metabolites in the semi-arid zone of Iran

This study aimed to determine the effect of using different sources of nitrogen to supply part of degradable intake protein needs in lactating goat performance and its effect on excretion of microbial purine derivatives and blood metabolites. Thirty-two lactating Saanen goats (body weight 38.85 ± 2.14 kg and 1979 ± 0.25 gday-1milk yield) were used in a one-way ANOVA completely randomized design. Goats were assigned to the following treatments for a 10-wk experimental period: 1) Control (canola meal as a nitrogen source); 2) Urea (0.5% urea); 3) Optigen (0.55% Optigen-Alltech.Inc., Lexington, KY) and 4) Polymer-Coated Urea (PCU-international patent number: A01K5/00, 0.7% PCU) based on dry mater intake. Non-protein nitrogen groups had a comparative effect (p > 0.05) between control and other treatments on milk composition, microbial protein synthesis and they affected on blood factors including urea, cholesterol, and ALT. Dry matter intake decreased (p > 0.05) in PCU, Optigen, Urea than Control goats. Synthesis of microbial protein in PCUgoats was 22.5 g day-1and it was greater (p > 0.05) than other treatments. Plasma cholesterol was increased in PCUand Optigen, whereas urea concentration was increased in Urea and Control goats. Milk production was higher in PCUthan Urea and Control. Feed conversion ratio was improved (p > 0.05) in PCU and Optigengoats versusother treatments.This study demonstrated that polymer-coated ureacan be utilized as a nitrogen source and improve goats milk performance.(AU)

How does reproduction account for dairy farm sustainability?

Sustainability - the new hype of the 21st century has brought discomfort for the government and society. Sustainable agriculture is essential to face our most concerning challenges: climate change, food security, and the environmental footprint, all of which add to consumers' opinions and choices. Improvements in reproductive indexes can enhance animal production and efficiency, guaranteeing profit and sustainability. Estrus detection, artificial insemination (AI), embryo transfer (ET), estrus synchronization (ES), and multiple ovulations are some strategies used to improve animal reproduction. This review highlights how reproductive strategies and genetic selection can contribute to sustainable ruminant production. Improved reproductive indices can reduce the number of nonproductive cows in the herd, reducing methane emissions and land use for production while preserving natural resources.(AU)

Prediction of health disorders in dairy cows monitored with collar based on binary logistic analysis / Previsão de distúrbios de saúde em vacas leiteiras monitoradas com base em coleira sobre análise logística binária

The objective of this study was to analyze data on physical activity and rumination time monitored via collars at the farm coupled with milk yield recorded by the rotary milking system to predict cows based on several disorders using the binary Logistic regression conducted with R software. Data for metritis (n=60), mastitis (n=98), lameness (n=35), and digestive disorders (n=52) were collected from 1,618 healthy cows used to construct the prediction model. To verify the feasibility and adaptability of the proposed method, we analyzed data of cows in the same herd (herd 1) not used to construct the model, and cows in another herd (herd 2) with data recorded by the same type of automated system, and led to detection of 75.0%, 64.2%, 74.2%, and 76.9% animals in herd 1 correctly predicted to suffer from metritis, mastitis, lameness, and digestive disorders, respectively. For cows in herd 2, 66.6%, 58.8%, 80.7%, and 71.4% were correctly predicted for metritis, mastitis, lameness, and digestive disorders, respectively. Compared with traditional clinical diagnoses by farm personnel, the algorithm developed allowed for earlier prediction of cows with a disorder.

Os objetivos deste estudo foram analisar dados sobre a atividade física e o tempo de ruminação monitorados através de coleiras na fazenda junto com a produção de leite registrada pelo sistema rotativo de ordenha para prever vacas com base em vários distúrbios utilizando o software de regressão logística binária realizado com o software R. Dados para metrite (n=60), mastite (n=98), manqueira (n=35) e distúrbios digestivos (n=52) foram coletados de 1.618 vacas saudáveis foram usados para construir o modelo de previsão. Para verificar a viabilidade e adaptabilidade do método proposto, analisamos os dados de vacas do mesmo rebanho (rebanho 1) não utilizadas para construir o modelo, e vacas de outro rebanho (rebanho 2) com dados registrados pelo mesmo tipo de sistema automatizado, e levamos à detecção de 75,0%, 64,2%, 74,2%, e 76,9% de animais do rebanho 1 previstos corretamente para sofrer de metrite, mastite, manqueira e distúrbios digestivos, respectivamente. Para as vacas do rebanho 2, 66,6%, 58,8%, 80,7% e 71,4% foram previstos corretamente para metrite, mastite, manqueira e distúrbios digestivos, respectivamente. Em comparação com os diagnósticos clínicos tradicionais feitos pelo pessoal da fazenda, o algoritmo desenvolvido permitiu a previsão antecipada de vacas com um distúrbio.

Genetic parameters and genetic trends for production traits in dairy Gir cattle / Parâmetros genéticos e tendências genéticas de características de produção de bovinos Gir Leiteiro

The objective of this research was to estimate genetic parameters and genetic trends (GT) for 305-day milk yield (MY305) and 305-day fat yield (FY305) of purebred Dairy Gir animals of the National Dairy Gir Breeding Program. The restricted maximum likelihood method was used in an animal model. GT were obtained via linear regression and divided into two periods (1935-1992 and 1993-2013 for PL305; 1935-1992 and 1993-2010 for MY305). The estimated heritabilities were 0.23 (MY305) and 0.10 (FY305). The GT (kg/year) values for MY305 in the 2nd period for measured females (25.49), females (26.11), and males (35.13) were higher than those found in the 1st period (2.52; 2.06, and 1.00, respectively). The heritability estimated for MY305 confirmed the possibility of genetic improvement by selection and indicated a lower additive genetic effect on FY305 of purebred animals. The genetic progress for MY305 in all purebred population is denoted by the more expressive gains found from 1990's, when the first bull catalogs were published.

Objetivou-se estimar os parâmetros genéticos e tendências genéticas (GT) para produção de leite (MY305) e produção de gordura (FY305), ambas em 305 dias, de animais puros Gir Leiteiro, integrantes do Programa Nacional de Melhoramento do Gir Leiteiro. Foi utilizada a metodologia da máxima verossimilhança restrita em modelo animal. As GT foram obtidas via regressão linear e divididas em dois períodos (1935-1992 e 1993-2013 para PL305; 1935-1992 e 1993-2010 para MY305). As herdabilidades foram de 0,23 (MY305) e 0,10 (FY305). Para PL305, as GT (kg/ano) do 2º período para fêmeas mensuradas (25,49), fêmeas (26,11) e, machos (35,13) foram claramente superiores às do 1º período (2,52; 2,06 e 1,00; respectivamente). A estimativa de herdabilidade para MY305 reafirma ser possível melhoramento genético por meio de seleção, enquanto para FY305 sugere uma menor influência genética aditiva em animais puros. O progresso genético para MY305 em toda a população pura está evidenciado pelos ganhos mais expressivos, observados a partir da década de 90, quando foram divulgados os primeiros sumários de touros.

Breed and heterosis effects on reproduction and production traits of Girolando cows

The objective of this study was to evaluate the breed and heterosis effects on reproductive traits, test-day milk yield, and 305-day milk yield in different lactations of crossbred Girolando cows. Data consisted of test-day milk yield records of first (118,831 records), second (63,227), and third lactation (44,512) and their relative productive (test-day milk yield, 305-day milk yield, and lactation length) and reproductive (age at first calving, calving interval, days open, and dry period) records of 35,582 Girolando cows from Brazil, collected from 1998 to 2014. The heterosis effect of the evaluated traits in Girolando cattle was estimated by MIXED procedure in SAS. Girolando cows showed a negative (favorable) and significant heterosis effect for reproductive traits. The dry periods between the first and second calving and between the second and third calving showed the greatest gains in heterosis (21.93 and 10.41%, respectively). All the evaluated productive traits showed a significant and similar heterosis effect between the three lactations. The use of crossbreeding strategies between the Holstein and Gyr breeds, instead of using the pure breed, is indeed a good alternative to increase the economic efficiency of the dairy activity in the different production systems in tropical environments.(AU)

Effects of milking system in suckling period on growth, reproduction traits, and milk yield of East Friesian-cross dairy sheep

The main objective of this study was to determine the effects of milking system on growth, reproduction, and milk yield and composition of East Friesiancross (Tahirova) dairy sheep that were milked in the evening during the suckling period. A total of 43 Tahirova ewes and 58 lambs were used in the present study. One of the groups was milked in the evening (evening milked; EM) before coming together with their lambs, and the other group was not (not milked in the evening; NEM). Morning milking was performed in both groups during the study. Lambs in both groups were individually weaned at the age of 60 days. There was no statistical difference between the lambs' live weight at weaning in the EM and NEM groups, determined to be 23.46 and 24.11 kg, respectively. Live weight values of lambs were similar in the groups at ages of up to 180 days. The reproductive characteristics of ewe lambs in the EM and NEM groups, having similar growth rates and a similar live weight and body condition in the first estrus stages, were also similar. The return rate and frequency of return were close in both groups of ewe lambs. Milk yield of the NEM group was significantly higher than that of the EM group before and after weaning. However, in groups with similar lactation milk yield and length, the total marketable milk yield was higher in the suckling period of the EM group. The milking system in suckling period of Tahirova ewes does not significantly affect growth, average daily gain, and reproductive characteristics. Milk yield in the NEM group before and after weaning was significantly higher than the EM group, but the total marketable milk yield was higher in the EM group.(AU)

Estimation of genetic parameters in dairy production in girolando cattle / Estimação de parâmetros genéticos na produção leiteira em bovinos girolando

Milk production is an important economic activity in Brazil. Dairy farmers would benefit from animal breeding programs that aid in identification and selection of animals with the best cost/benefit ratio to maximize productivity, and additionally provide advice on disposal of less productive animals. This study aims to estimate the heritability and repeatability of milk production corrected for 305 days (PL305) in a herd of Girolando cattle. We analyzed 528 lactations in 251 cows. For the analysis, uniform a priori distribution was defined for systematic effects. Gaussian and inverted Wishart distributions were defined as a priori distributions for random effects. The variance components were estimated based on Bayesian inference using the MCMCglmm function available in the MCMCglmm package of the R software. Convergence was verifed with the Geweke test available in the R software. The heritability and repeatability were estimated from the variance component results. Heritability was at 0.28, suggesting that selection for the milk production trait leads to efficient genetic progress in the herd. Phenotypic variance was mainly due to environmental variance; therefore, the phenotype of individuals should not be considered as indicator for additive genetic variance. Repeatability was at 0.93, indicating that the first performance of the animals based on milk production average is a good indicator of the second, and the data could be used for disposal decisions.(AU)

A produção de leite é uma das atividades econômicas mais importantes da agropecuária brasileira. Produtores podem usufruir de programas de melhoramento genético que permitem a identificação dos melhores animais e sua seleção para maximizar a produtividade com a melhor relação custo/benefício, além do aconselhamento do descarte de animais menos produtivos. Objetivou-se estimar a herdabilidade e repetibilidade da produção de leite corrigida para 305 dias (PL305) de um rebanho de bovinos da raça Girolando. Foram analisadas 528 lactações de 251 vacas. Para análise foi definida a distribuição uniforme a priori para efeitos sistemáticos. As distribuições de Wishart gaussiana e invertida foram definidas como distribuições a priori para efeitos aleatórios. Os componentes de variância foram estimados utilizando inferência bayesiana pela função MCMCglmm disponível no pacote MCMCglmm do software R. A convergência foi verificada pelo teste de Geweke disponível no software R. Após a obtenção dos componentes de variância foram estimados a herdabilidade e repetibilidade. A herdabilidade observada foi 0,28, o que sugere que a seleção para esta característica resultará em progresso genético eficiente no rebanho. A maior parte da variância fenotípica é devido a variância ambiental, com isso, o fenótipo dos indivíduos não é um bom indicador da variância genética aditiva. A repetibilidade foi de 0,93, indicando que o primeiro desempenho dos animais é considerado um bom indicador do segundo, podendo ser utilizadas em decisões de descarte.(AU)

Supplementation strategies for lactating F1 Holstein x Zebu cows on deferred pastures / Estratégias de suplementação para vacas F1 Holandês x Zebu em lactação em pasto diferido

The objective of this study was to evaluate the effects of different concentrate supplementation strategies to lactating F1 Holstein x Zebu cows managed on deferred signal grass pasture on milk yield, composition and body weight gain. Thirty-six F1 Holstein x Zebu cows with average days in milk of 102 ± 10 and body weight of 501 ± 19 kg were allotted to a 4 x 5 completely randomized factorial design, with four feeding strategies and five weeks of evaluation. The treatments consisted of four nutritional strategies: deferred pasture as a source of roughage + 700 grams of protein supplement (PDPI); deferred pasture as a source of roughage + 1,200 grams of protein supplement (PDPII); deferred pasture + 15 kilograms of corn silage (natural basis) + 1,200 grams of protein supplement (PDSP) and corn silage (ad libitum) + 700 grams of protein supplement (CSS). There was no interaction (P = 0.99) between supplementation strategies and test days on milk yield and chemical composition. The mean milk yield of cows managed on PDPI, PDPII and PDSP was 11.50 kg/day (P > 0.05), which was 14.30% lower than that of cows managed on CSS. Fat content (P < 0.01), protein (P < 0.01), lactose (P < 0.01), defatted dry extract (DDE) (P< 0 .01), total solids (P < 0.01) and milk casein (P < 0.01) were affected by different supplementation strategies. F1 Holstein x Zebu cows on deferred Urochloa decumbens cv. Basilisk pasture and supplemented with concentrate maintains milk production at 11.50 kg with normal composition, maintaining satisfactory body weight and condition score.(AU)

O objetivo deste estudo foi avaliar os efeitos de diferentes estratégias de suplementação com concentrado para vacas F1 Holandês x Zebu em lactação manejadas em pastagem de capim-braquiária diferida sobre a produção, composição e ganho de peso corporal do leite. Trinta e seis vacas F1 Holandês x Zebu com média de dias em leite de 102 ± 10 e peso corporal de 501 ± 19 kg foram distribuídas em um planejamento fatorial 4 x 5 inteiramente casualizado, com quatro estratégias de alimentação e cinco semanas de avaliação. Os tratamentos consistiram em quatro estratégias nutricionais: pasto diferido como fonte de volumoso + 700 gramas de suplemento protéico (PDPI); pastagem diferida como fonte de volumoso + 1.200 gramas de suplemento protéico (PDPII); pastagem diferida + 15 quilos de silagem de milho (base natural) + 1.200 gramas de suplemento protéico (PDSP) e silagem de milho (ad libitum) + 700 gramas de suplemento protéico (CSS). Não houve interação (P = 0,99) entre as estratégias de suplementação e os dias de teste na produção e composição química do leite. A produção média de leite das vacas manejadas com PDPI, PDPII e PDSP foi de 11,50 kg / dia (P > 0,05), que foi 14,30% menor que a das vacas manejadas com CSS. O teor de gordura (P < 0,01), proteína (P < 0,01), lactose (P < 0,01), extrato seco desengordurado (DDE) (P < 0,01), sólidos totais (P < 0,01) e caseína do leite (P < 0,01) foram afetados por diferentes estratégias de suplementação. Vacas F1 Holandês x Zebu em Urochloa decumbens diferida cv. O pasto de Basilisk e suplementada com concentrado mantém a produção de leite em 11,50 kg com composição normal, mantendo peso corporal e escore de condição satisfatórios.(AU)

Productive and reproductive performance of crossbred dairy heifers with induced lactation and efficacy of antimicrobial therapy associated with internal teat sealants / Desempenho produtivo e reprodutivo de novilhas com lactação induzida e eficácia da terapia antimicrobiana associada com selante interno de tetos

This study evaluated (a) the efficacy of an association between injectable antibiotic therapy and sealant (ATBS) on milk yield (MY), somatic cell count (SCC), and prevalence of intramammary infections (IMI); and (b) the efficacy of gonadotropin-releasing hormone (GnRH) on follicular cyst (FCs) resolution (cyclicity at the 45th day in milk; DIM) and cumulative pregnancy rate (CPR) in heifers submitted to a lactation induction protocol (LIP). A total of 114 crossbred (Holstein × Jersey) heifers, with 34.7 ± 4.8 months and 439 ± 56.35 kg were submitted to LIP. On the 5th day of the LIP, the heifers were assigned to (i) ATBS (n = 57) with 7 mg/kg of norfloxacin associated with sealant and (ii) Control 1 (n = 57; CONT1) with no treatments. Lactation began on the 21st day of LIP and the 15th DIM, FCs were diagnosed and 106 heifers were randomized into two treatment groups with 53 heifers each: (i) GnRH (5 mL injectable GnRH) and (ii) Control 2 (CONT2; no treatment). Of the 114 heifers initially induced, 83.33% (n = 95) responded to LIP with an average MY of 15.19 kg/milk/day during 22 weeks of lactation. In the first 14 DIM, the IMI prevalence was 18% and 28% for heifers ATBS and CONT1 treated, respectively. Additionally, coagulase-negative Staphylococcus was the most frequently isolated group of pathogens. Mammary quarters that received ATBS treatment had a lower risk of IMI and SCC than CONT1. The cyclicity at 45 DIM was 68% (ATBS) and 35% (CONT1), and 57% and 46% for animals in the GnRH and CONT2. CPR was 60% in the ATBS group and 89% in CONT1, but GnRH treatment did not affect the CPR. In conclusion, LIP was effective in stimulating MY in heifers, and the IMI prevalence decreased with ATBS treatment. Also, the use of GnRH did not affect the FC regression, cyclicity at 45 DIM, and CPR.(AU)

Este estudo avaliou a (i) eficácia da associação entre antibioticoterapia injetável e selante interno de tetos (ATBS) na produção de leite (PL), contagem de células somáticas (CCS), e prevalência de infecções intramamárias (IIM); e (ii) eficácia do hormônio liberador de gonadotrofina (GnRH) na resolução de cistos foliculares (CFs), ciclicidade ao 45º dia em lactação (DEL) e taxa de prenhez cumulativa (TPC) em novilhas submetidas a um protocolo de indução de lactação (PIL). Um total de 114 novilhas mestiças (Holandês × Jersey), com 34,7 ± 4,8 meses e 439 ± 56,35 kg foram submetidas ao PIL. No 5º dia do PIL, as novilhas receberam: (i) ATBS (n = 57) com 7 mg/kg de norfloxacina associada ao selante interno de tetos e (ii) Controle 1 (n = 57; CONT1) sem tratamento. A lactação teve início no 21º dia do PIL e no 15º DEL, foram diagnosticados CFs e 106 novilhas foram agrupadas em dois grupos de tratamento com 53 novilhas em cada: (i) GnRH (5 mL de GnRH injetável) e (ii) Controle 2 (CONT2; sem tratamento). Das 114 novilhas inicialmente induzidas, 83,33% (n = 95) responderam ao PIL com PL média de 15,19 kg/leite/d durante 22 semanas de lactação. Nos primeiros 14 DEL a prevalência de IIM foi de 18% e 28% para as novilhas tratadas com ATBS e CONT1, respectivamente. Além disso, estafilococos coagulase negativa foram o grupo de patógenos mais frequentemente isolados. Quartos mamários tratados com ATBS tiveram menor risco (0,56) de IIM e menor CCS do que CONT1. A ciclicidade a 45 DEL foi de 68% (ATBS) e 35% (CONT1), e 57% e 46% para os animais no GnRH e CONT2. A TPC foi de 60% no grupo ATBS e 89% no CONT1, porém o tratamento com GnRH não afetou a TPC. Em conclusão, o PIL foi eficaz em estimular a PL em novilhas tardias e a prevalência de IIM diminiuiu com o tratamento ATBS. Além disso, o uso de GnRH não afetou a regressão de CF, ciclicidade em 45 DEL e a TPC.(AU)

Multidimensional scaling analysis for investigating relations between milk yield and fertility parameters / [Análise multidimensional de escala para investigar as relações entre o rendimento do leite e os parâmetros de fertilidade]

Milk yield and fertility traits in dairy cattle and their relationship with the influencing factors were investigated using multidimensional scaling analysis (MDS) in this study. The study focused on the relationship between lactation length, 305-day milk yield, actual milk yield and peak remaining days from milk yield characteristics, and service period, dry period, insemination per conception and calving interval from fertility traits, as well as the influencing factors such as calving age, lactation number, birth season, and birth year. When the MDS results were examined, it was discovered that all the traits had close Euclidean distances from each other, save for the birth season and birth year. As a result of MDS analysis, R2 and Stress Coefficient were calculated as 88.4% and 0.099, respectively. Consequently, the selection direction was tried to be identified by determining the milk yield and fertility traits and the relationship between these traits and the influencing factors through the MDS analysis and it was concluded that the MDS method could be employed in this field.

As características de produção de leite e fertilidade do gado leiteiro e sua relação com os fatores de influência foram investigadas utilizando a análise de escala multidimensional (MDS) neste estudo. O estudo concentrou-se na relação entre o tempo de lactação, produção de leite de 305 dias, produção real de leite e pico de dias restantes das características de produção de leite, e período de serviço, período seco, inseminação por concepção e intervalo de partos dos traços de fertilidade, bem como os fatores influenciadores como idade de parição, número de lactação, época de nascimento e ano de nascimento. Quando os resultados do MDS foram examinados, descobriu-se que todos os traços tinham distâncias Euclidianas próximas umas das outras, exceto para a época de nascimento e ano de nascimento. Como resultado da análise do MDS, o R2 e o Coeficiente de Estresse foram calculados como 88,4% e 0,099, respectivamente. Consequentemente, tentou-se identificar a direção da seleção determinando os traços de produção e fertilidade do leite e a relação entre estes traços e os fatores de influência através da análise MDS e concluiu-se que o método MDS poderia ser empregado neste campo.

Elevated temperature-humidity index induces physiological, blood and milk alterations in Holstein cows in a more pronounced manner than in ½ and ¾ Holstein × Gir

Bos taurus taurus and Bos taurus indicus cattle subspecies present different capabilities in coping with situations of elevated temperatures, the latter being more tolerant to heat stress. Thus, some breeding programs crossed these subspecies to produce a high producing yet heat-tolerant breed (Girolando). Nineteen Holstein (H100) and 19 Girolando cows [(½ Holstein × Gir (H50) and ¾ Holstein × Gir (H75)] with similar milk production were used in a six-day experiment to evaluate the consequences of heat stress due to shade deprivation on their physiological, blood and milk traits. Cows were exposed to a non-shaded environment between morning (06:00h; GMT -3:00) and evening milking (14:30h; GMT -3:00) with access to water ad libitum. Procedures were conducted before morning and evening milkings. Physiological parameters related to mechanisms of heat dissipation were measured, as well as the milk composition. Blood traits were evaluated. The temperature-humidity index (THI) was calculated. Statistical procedures included analysis of variance, correlation, and principal factors. THI was elevated during the trial and negatively impacted physiological, milk, and blood parameters in H100, H75, and H50. Alterations in physiology, milk stability, milk composition, and blood traits were more pronounced in H100. Holstein cows presented changes in physiological parameters in a more pronounced manner and in some milk and blood traits related to the reduced capability of this breed in dealing with elevated THI. The similarity in milk production levels excludes this parameter as a justification for differences in heat tolerance, with genetic composition being the main reason for these results.(AU)

Effects of an injectable mineral supplement on physiological responses and milk production of heat-stressed Holstein cows

Summer heat stress in northwest Mexico compromises the physiological thermoregulation capacity and productive performance of lactating Holstein cows, and supplementation of minerals appears to reduce the adverse impact of heat stress in cattle. The objective herein was to evaluate the effects of an injectable mineral supplement containing phosphorus, selenium, potassium, magnesium, and copper on physiological responses, milk production, and milk composition of Holstein cows exposed to heat stress. Sixteen cows were blocked by parity and assigned to one of two treatments (n = 8) using a randomized complete block design: 1) control cows and 2) mineral-treated cows. All cows were exposed to environmental heat stress conditions (i.e., temperature-humidity index = 79.4 ± 4.3 units). No study variable was affected (P ≥ 0.20) by the treatment x sampling day interaction. While the mineral supplement did not affect any physiological variable in the afternoon, this treatment decreased breaths per min (P = 0.01) and most body surface temperatures (P ≤ 0.06; head, shoulder, leg, right-flank, and udder) in the morning. There was no effect (P = 0.37) of the mineral supplementation on milk yield but increased (P ≤ 0.03) the percentages of solids non-fat, protein, lactose, and density in the milk. In conclusion, Holstein cows' physiological thermoregulation and milk composition experiencing summer heat stress were improved by applying an injectable mineral supplement.(AU)

Elevated temperature-humidity index induces physiological, blood and milk alterations in Holstein cows in a more pronounced manner than in ½ and ¾ Holstein × Gir

Bos taurus taurus and Bos taurus indicus cattle subspecies present different capabilities in coping with situations of elevated temperatures, the latter being more tolerant to heat stress. Thus, some breeding programs crossed these subspecies to produce a high producing yet heat-tolerant breed (Girolando). Nineteen Holstein (H100) and 19 Girolando cows [(½ Holstein × Gir (H50) and ¾ Holstein × Gir (H75)] with similar milk production were used in a six-day experiment to evaluate the consequences of heat stress due to shade deprivation on their physiological, blood and milk traits. Cows were exposed to a non-shaded environment between morning (06:00h; GMT -3:00) and evening milking (14:30h; GMT -3:00) with access to water ad libitum. Procedures were conducted before morning and evening milkings. Physiological parameters related to mechanisms of heat dissipation were measured, as well as the milk composition. Blood traits were evaluated. The temperature-humidity index (THI) was calculated. Statistical procedures included analysis of variance, correlation, and principal factors. THI was elevated during the trial and negatively impacted physiological, milk, and blood parameters in H100, H75, and H50. Alterations in physiology, milk stability, milk composition, and blood traits were more pronounced in H100. Holstein cows presented changes in physiological parameters in a more pronounced manner and in some milk and blood traits related to the reduced capability of this breed in dealing with elevated THI. The similarity in milk production levels excludes this parameter as a justification for differences in heat tolerance, with genetic composition being the main reason for these results.

Effects of an injectable mineral supplement on physiological responses and milk production of heat-stressed Holstein cows

Summer heat stress in northwest Mexico compromises the physiological thermoregulation capacity and productive performance of lactating Holstein cows, and supplementation of minerals appears to reduce the adverse impact of heat stress in cattle. The objective herein was to evaluate the effects of an injectable mineral supplement containing phosphorus, selenium, potassium, magnesium, and copper on physiological responses, milk production, and milk composition of Holstein cows exposed to heat stress. Sixteen cows were blocked by parity and assigned to one of two treatments (n = 8) using a randomized complete block design: 1) control cows and 2) mineral-treated cows. All cows were exposed to environmental heat stress conditions (i.e., temperature-humidity index = 79.4 ± 4.3 units). No study variable was affected (P ≥ 0.20) by the treatment x sampling day interaction. While the mineral supplement did not affect any physiological variable in the afternoon, this treatment decreased breaths per min (P = 0.01) and most body surface temperatures (P ≤ 0.06; head, shoulder, leg, right-flank, and udder) in the morning. There was no effect (P = 0.37) of the mineral supplementation on milk yield but increased (P ≤ 0.03) the percentages of solids non-fat, protein, lactose, and density in the milk. In conclusion, Holstein cows' physiological thermoregulation and milk composition experiencing summer heat stress were improved by applying an injectable mineral supplement.

Use of quali-quantitative feeding practices criteria in typology of smallholders' dairy production systems

This study aimed to typify smallholders' dairy systems using quali-quantitative measures of feeding practices and detect the main discriminatory elements identifying the systems. We collected data from 30 farms distributed in 10 municipalities in the eastern region of Rio Grande do Sul, Brazil, using a survey with semi-structured questions, in addition to bimonthly observations of milking and feeding practices. Multivariate analysis based on principal factors and cluster analysis were performed. Multiple linear regressions were made between the principal factors scores and variables of milk production and composition. Three principal factors with eigenvalues ≥1.0 explained 58.9% of the total variance. The original variables with the highest factor loading values were production scale and feeding practices involving greater quantities of byproducts; use of corn silage and sugarcane; and commercial and farm-made concentrate for principal factor 1, principal factor 2, and principal factor 3, respectively. Milk yield and concentrations of lactose and solids non-fat increased linearly with principal factor 1 and principal factor 3 but decreased linearly with principal factor 2. Observations were grouped into three clusters. Farm area and quantity of corn silage and byproducts were the most important variables to set the clusters. The use of quali-quantitative feeding practices criteria to characterize dairy systems is effective to identify the opportunities for improving milk production and composition. Whereas high inclusion of sugarcane as roughage was detrimental for milk production, moderate supply of concentrate and byproducts enhanced milk yield without compromising milk composition.

Influence of lactation number and parity on milk yield of Saanen goat's breed / [Influência do número de lactação e paridade na produção de leite da raça de cabras Saanen]

The aim of this research was to determine the influence of lactation number and parity on milk yield of Saanen goat's breed. It has been concluded that milk yield was higher for goats that had given birth to twins and three kids than for goats that had given birth to a single kid (P<0.05). The longevity has a great positive impact on production, given that goats in the fifth lactation produced more milk than goats in first or second lactation (P<0.05), while goats in the sixth lactation still produced more milk than goats in first lactation (P<0.05). During the period from 2014- 2019, the research was conducted on a farm of multiparous Saanen goats in Vojvodina (northern part of Serbia). In the observed period, the farm had between 350 and 400 goats per milking, and the research included a total of 1,628 concluded lactations, within which the first lactations were the most 484, then the second 381. According to the number of lactations, goats were grouped into classes from one to seven and from one to three for parity. By comparing each individual lactation, it was determined that in first lactation goats produced significantly lower milk than goats in the rest lactations(P<0.05), except the seventh. Research has shown that lactation number has a significant influence on milk yield (P=0.00). Increasing the fertility of goats significantly affects the production capacity of dairy goats, since does with a larger number of kids in the litter had a significantly higher milk production (P<0.05). Due to the larger number of kids in the litter, milk production also increases. Likewise, it is assumed that the increase in milk yield of goats with two and three kids is a consequence of a larger placenta, i.e. stronger lactogenic activity during pregnancy.(AU)

O objetivo desta pesquisa foi determinar a influência do número de lactações e da paridade na produção de leite da raça de cabras Saanen. Concluiu-se que a produção de leite era maior para caprinos que haviam dado à luz gêmeos e três cordeiros do que para caprinos que haviam dado à luz um único cordeiro (P<0,05). A longevidade tem um grande impacto positivo na produção, dado que as cabras na quinta lactação produziram mais leite do que as cabras na primeira ou segunda lactação (P<0,05), enquanto as cabras na sexta lactação ainda produziram mais leite do que as cabras na primeira lactação (P<0,05). Durante o período de 2014- 2019, a pesquisa foi realizada numa fazenda de cabras Saanen multipares em Voivodina (parte norte da Sérvia). No período observado, a fazenda tinha entre 350 e 400 cabras por ordenha, e a pesquisa incluiu um total de 1.628 lactações concluídas, dentro das quais as primeiras lactações foram as mais 484, depois as segundas 381. De acordo com o número de lactações, as cabras foram agrupadas em classes de um a sete e de um a três para paridade. Comparando cada lactação individual, determinou-se que na primeira lactação as cabras produziram leite significativamente menor do que as cabras nas demais lactações (P<0,05), exceto a sétima. Pesquisas mostraram que o número de lactações tem uma influência significativa na produção de leite (P=0,00). O aumento da fertilidade das cabras afeta significativamente a capacidade de produção de caprinos leiteiros, já que com um número maior de cabritos na ninhada a produção de leite foi significativamente maior (P<0,05). Devido ao maior número de cabritos na ninhada, a produção de leite também aumenta. Da mesma forma, assume-se que o aumento na produção de leite de cabras com dois e três cabritos é uma consequência de uma placenta maior, ou seja, de uma atividade lactogênica mais forte durante a gestação.(AU)

Relationship between metabolic profile, diseases, productive and reproductive performance in highproducing Holstein cows in the postpartum period / Relação entre o perfil metabólico, doenças, desempenho produtivo e reprodutivo de vacas Holandesas recém-paridas de alta produção

The present study aimed to monitor Holstein cows in the postpartum period, and to evaluate the occurrence of clinical diseases and their relationship with metabolic profile, milk yield and composition, and reproductive performance. One hundred and five Holstein cows, 32 primiparous and 73 multiparous, from two dairy herds in Arapoti, Paraná State, were clinically monitored up to ten days after calving. The clinical occurrences diagnosed were: dystocia, metritis, retained placenta, clinical hypocalcemia, displaced abomasum, mastitis, pneumonia, and digital dermatitis. Blood samples were collected at one, two, five, and ten days postpartum for analysis of non-esterified fatty acids (NEFA), ß-hydroxybutyrate (BHB), and total calcium. Individual milk yield was measured up to 100 days in milk (DIM), and the first test-day was evaluated for milk composition. Statistical analyses were conducted using the MIXED procedure of SAS, and the fixed effects of farm (A and B), parity (primiparous and multiparous), and occurrence of clinical diseases (sick and healthy cows) were included. Forty-eight cows (45.7%) had one or more clinical occurrences. In these sick cows, the BHB concentration at five DIM was higher (P = 0.06) than in healthy cows; 0.78 and 0.57 mmol L-1, respectively. Regarding milk yield, cows with one or more clinical occurrences had lower (P < 0.01) daily milk yield up to 30 DIM, and had a tendency of lower (P = 0.09) accumulated production up to 100 DIM than healthy cows. Sick cows had a tendency to show lower (P = 0.08) milk total solids content than healthy cows; 12.04 and 12.60%, respectively. There were no significant differences between sick and healthy animals in the remaining milk components, or the reproductive parameters assessed. The differences observed for days in the first artificial insemination (AI), AI number, and days open occurred due to the effect of the herd.(AU)

O objetivo deste estudo foi monitorar vacas Holandesas no pós-parto e avaliar a ocorrência de doenças clínicas e sua relação com o perfil metabólico, a produção de leite e sua composição e o desempenho reprodutivo. Foram monitoradas clinicamente durante 10 dias após o parto, 105 vacas da raça Holandesa, 32 primíparas e 73 multíparas, de dois rebanhos leiteiros em Arapoti, Paraná. As ocorrências clínicas diagnosticadas foram: distocia, metrite, retenção de placenta, hipocalcemia clínica, deslocamento de abomaso, mastite, pneumonia e dermatite digital. Amostras de sangue foram coletadas nos dias 1, 2, 5 e 10 após o parto para análises de ácidos graxos não-esterificados (AGNE), ß-hidroxibutirato (BHB) e cálcio total. A produção de leite individual foi mensurada até 100 dias em leite (DEL) e para a composição do leite foi avaliado o primeiro controle leiteiro oficial após o parto. As análises estatísticas foram conduzidas pelo procedimento MIXED do SAS e foram incluídos os efeitos fixos de fazenda (A e B), paridade (primíparas e multíparas) e ocorrência de doenças clínicas (vacas doentes e saudáveis). Quarenta e oito vacas (45,7%) apresentaram uma ou mais doenças clínicas. Nestas vacas doentes a concentração de BHB no 5o dia pós-parto foi superior (P = 0,06) a de vacas saudáveis; 0,78 e 0,57 mmol L-1, respectivamente. Em relação a produtividade, vacas com uma ou mais doenças clínicas apresentaram menores (P < 0,01) produções diárias até 30 DEL e tendência de menores (P = 0,09) produções acumuladas até 100 DEL em relação a vacas sadias. Vacas doentes apresentaram uma tendência de menor (P = 0,08) porcentagem de sólidos totais no leite do que vacas saudáveis; 12,04 e 12,60%, respectivamente. Não houve diferenças significativas entre animais doentes e saudáveis para os outros componentes do leite, bem como nos parâmetros reprodutivos avaliados. As diferenças observadas para dias até a primeira inseminação artificial (IA), número de IA e dias abertos ocorreram devido ao efeito de rebanho.(AU)

Linear modeling analysis using for determining the factors affecting 305-day milk yield / [Análise de modelagem linear usado para determinar os fatores que afetam o rendimento leiteiro de 305 dias]

The purpose of this study was to model the factors affecting the 305-day milk yield of dairy cows by using Automatic Linear Modeling Technique (ALM). The data set of this study consisted of eight different cow breeds grown in eight province of Turkey. Results of ALM showed that the accuracy of the model was 64.2 % means that 64.2% of the variation in the 305-day milk yield could be explained by the constructed model. Created model was consisted of four factors namely the Breed, Lactation Length, Parity, and Province. Therefore, those selected factors were more efficient than the others in predicting the 305-day milk yield.(AU)

O objetivo deste estudo foi modelar os fatores que afetam a produção de leite das vacas leiteiras em 305 dias, utilizando a Técnica de Modelagem Linear Automática (ALM). O conjunto de dados deste estudo consistia em oito raças diferentes de vacas cultivadas em oito províncias da Turquia. Os resultados da ALM mostraram que a precisão do modelo era de 64,2% significa que 64,2% da variação na produção de leite de 305 dias poderia ser explicada pelo modelo construído. O modelo criado consistia de quatro fatores: Raça, Comprimento da Lactação, Paridade e Província. Portanto, esses fatores selecionados foram mais eficientes do que os outros na previsão da produção de leite de 305 dias.(AU)

Use of sugar cane to feed lactating dairy goats / [Uso da cana-de-açúcar na alimentação de cabras leiteiras em lactação]

The aim of the present study was to assess the effects of replacing corn silage with sugarcane in the diet of lactating Saanen goats and to determine their intake and digestibility of nutrients, ingestive behavior, milk yield and composition. The experimental diets were composed of increasing levels (0, 33, 66 and 100%) of substitution in dry matter (DM). Twelve multiparous Saanen goats, with an average body weight of 45.2kg, average milk yield of 3.0kg day-1, distributed in a triple latin square experimental design (4 × 4) were used. The dry matter intake (DMI) and other nutrients were estimated through the difference between the total nutrient in the food offered and its total in the leftovers. The DMI, crude protein, neutral detergent fiber (NDF) and total digestible nutrients were not influenced, but the apparent digestibility of DM and NDF decreased. Feeding time and feeding efficiency were not influenced, the rumination and total chewing times increased, and the leisure time decreased, both linearly. Milk yield was not influenced by substitution levels, but corrected milk yield to 3.5% fat decreased. Sugar cane represents a dietary alternative for goats with medium milk yield in critical periods of forage, since it does not change the consumption of DM and milk yield, even with the apparent declining digestibility of some nutrients, influencing the ingestive behavior of the animals.(AU)

O objetivo do presente estudo foi avaliar os efeitos da substituição da silagem de milho por cana-de-açúcar na dieta de cabras Saanen em lactação e determinar a ingestão e a digestibilidade de nutrientes, o comportamento ingestivo, a produção e a composição do leite. As dietas experimentais foram compostas de níveis crescentes (0, 33, 66 e 100%) de substituição na matéria seca (MS). Doze cabras Saanen multíparas, com peso corporal médio de 45,2kg, produção média de leite de 3,0kg dia-1, foram distribuídas em delineamento experimental triplo quadrado latino (4 × 4). A ingestão de matéria seca (IMS) e de outros nutrientes foi estimada por meio da diferença entre o total de nutrientes nos alimentos oferecidos e o total nas sobras. A IMS, a proteína bruta, a fibra em detergente neutro (FDN) e os nutrientes digestíveis totais não foram influenciados, mas a digestibilidade aparente da MS e da FDN diminuiu. A produção de leite não foi influenciada pelos níveis de substituição, mas a produção de leite corrigida para 3,5% de gordura diminuiu. A cana-de-açúcar representa uma alternativa alimentar para cabras com produção média de leite em períodos críticos de forragem, pois não altera o consumo de MS e a produção de leite, mesmo diminuindo a digestibilidade aparente de alguns nutrientes e influenciando o comportamento ingestivo dos animais.(AU)

Influência da suplementação lipídica no desempenho de vacas leiteiras mantidas a pasto / Influence of lipid supplementation on grazing dairy cow performance

A adição de lipídios como suplemento para vacas leiteiras criadas a pasto tem recebido atenção nos últimos anos, principalmente devido ao aumento da produção de leite, necessidade de se elevar o nível de energia das dietas e contribuição positiva para algumas funções orgânicas. A manipulação industrial dos ácidos graxos tornou possível a utilização de lipídios na alimentação de ruminantes, ultrapassando os limites que apresentam alguma interferência no ambiente ruminal. No processo de tomada de decisão a respeito da escolha de alimentos a serem incluídos nas dietas de animais de alta produção, devem ser adotadas precauções a respeito dos níveis de inclusão nas dietas, respeitando os limites de toxidez apresentado pelos lipídios na flora do rúmen, capazes de comprometer as atividades metabólicas, variáveis ruminais, composição do leite e produtividade dos animais. Dessa forma, a presente revisão de literatura foi elaborada com o objetivo de abordar aspectos relacionados à utilização de suplementação lipídica nas variáveis ruminais e composição do leite de vacas leiteiras criadas a pasto.

The addition of lipids as a supplement for grazing dairy cows has received attention in recent years, mainly due to increased milk production, the need to rise the energy level of diets and the positive contribution to some organic functions. The industrial handling of fatty acids made it possible to use lipids in ruminant feed beyond the limits that can cause interference in the rumen environment. In the decision-making process regarding the choice of feed to be included in the diets of high yielding animals, precautions should be taken regarding the levels of inclusion in the diets, respecting the toxicity limits presented by the lipids in the rumen flora, metabolic activity, ruminal parameters, milk composition and animal productivity. Thus, this literature review was designed to address aspects related to the use of lipid supplementation in ruminal parameters and milk composition of grazing dairy cows.